"Nuclear Isomers" exist, which refers to excitation states inside the nucleus. What he is saying is that such a excited state in the nucleus makes the element 'more stable' than its ground state, and thus doesn't decay.

The previous discovery of Element 122 in thorium was shown to be incorrect at higher levels of accuracy; thus, it seems unlikely that this one will bear fruit, especially since roentgenium shouldn't be stable for more than seconds.
It still may bear out, but I consider that extremely unlikely.

Article says this guy held a vacuum above liquid gold, not boiling gold. The vacuum encourages evaporation by raising the vapor pressure of gold (and removing gas phase atoms there), but not to boiling. The difference between the melting and boiling points for gold is 1800K at 1 atm.

I'm also wondering how Marinov suspected it would be in gold. The only link I can find is that they're both group 11 elements, but by that logic you should be able to find tellurium in sulfur, which isn't the case.

Sulfur is more reactive, so the geological and chemical processes which form sulfur deposits also separate it from gold. Gold doesn't react with as many things as sulfur, so an element with similar characteristics will be more diluted in sulfur than in a gold deposit. On the other hand, if this element does indeed also travel with sulfur then there's a chance that larger amount might be in the larger sulfur deposits even if there's less per ton.

Goldschmidt Classification [wikipedia.org]. Although I too have my doubts about the stable Rg, there is some reason to the madness of expecting certain elements to be found with other ones.

111 has an odd number of protons which is strike number one. odd numbers of protons or neutrons are much less stable and strike number two is that the island of stability is for the most part concerning stability against fission and alpha radiation decay.
Strike number three is that the stability of isotopes of element 111 are markedly less stable than isotopes of elements 114-116

Take a look at this [wisc.edu].

Another factor affecting the stability of a nucleus is whether the number of protons and neutrons is even or odd. Among the 354 known stable isotopes, 157 (almost half) have an even number of protons and an even number of neutrons. Only five have an odd number of both kinds of nucleons

The reason why this is so is that nuclei just like atoms in chemistry have shells (in chemistry it's electrons with nuclei it's protons and neutrons) filled shells are more stable which is why there is an island of stability. The island of stability is centered around the magic numbers 114 (the number of protons) and 184 (the number of neutrons) magic numbers of either protons or neutrons tend to create more stable nuclei. nuclei with odd numbers of either are less stable in the same way that Fluorine is less stable chemically compared to Neon. The nuclear shell is not full and is therefore less stable to various modes of decay.

Your point concerning alpha and fission modes of decay is more likely to increase the half life significantly excluding electron capture and beta decay modes.

elements 114-116 have isotopes with half lives that are significantly higher than nuclei in the 100-113 range as these lower nuclei tend to have half lives measured in fractions of a second. The island of stability is a misnomer. It'd be far more accurate to say that it is an island of relative not absolute stability. The odds of finding any nuclei beyond uranium with a comparable half life or even stable nuclei is remote.

is the bond energy and fracture mechanics. For example, ceramic armor breaks into lots of very small particles when hit by a projectile: each fracture surface is created using energy from the incoming projectile, and hence dissipates the projectile's energy. Ceramics aren't very dense compared to tungsten or DU, but their fracture energies are very high. Density counts for projectiles because it's one of the parameters that determines the pressure at the impact point, which in turn is one of the parameters that predicts penetration efficacy. Tungsten is a little more dense than DU, not significantly so for projectile use. A DU projectile will catch fire when it penetrates armor, contributing to its destructive effects. Tungsten doesn't do this. DU is a low-level radiological hazard, tungsten isn't, so for cleaning up after a battle, tungsten is a better choice. DU may have some low-level chemical toxicity, but there's evidence that tungsten (when imbedded as particles under skin) is toxic as well. I speculate the choice of D vs W for projectiles is mainly economic (unless you need to incinerate the occupants of that tank you're killing), as I think DU is cheaper than W.

You are correct that pure DU would essentially be no more hazardous than other types of heavy metal pollution. However, the situation is more complex in reality.

Quoth the WHO [who.int]:

Spent uranium fuel from nuclear reactors is sometimes reprocessed in plants for natural uranium enrichment. Some reactor-created radioisotopes can consequently contaminate the reprocessing equipment and the DU. Under these conditions another uranium isotope, 236U, may be present in the DU together with very small amounts of the transuranic elements plutonium, americium and neptunium and the fission product technetium-99. However, the additional radiation dose following intake of DU into the human body from these isotopes would be less than 1%.

Somehow, I don't find that very reassuring ("Yay! Heavy metal toxicity with a side of biosequestered alpha & beta emitters!"). It seems much more likely that spent-fuel DU production would have less quality control care than the original enrichment process, but I could very well be mistaken.

I have heard it alleged that only the US uses spent reactor fuel to create DU for weapons and that other countries that produce DU weapons use only the byproduct from the enrichment stage. However, since I have no cite at the moment, I wouldn't assign that much credulity. Regardless, it does seem that in practice DU is not always pure as the driven snow.

Strictly speaking, he may be referring to a "structural isomer", but if so, it can only be defined in terms of other isomers, and further, it is a molecular distinction, not nuclear.

The term has different meanings in nuclear physics than in chemistry. In nuclear physics, it refers to an unusually long-lived excited state of the nucleus.