No, that is stupid. So stupid that it goes right past retarded, to "quotes like that are why some people believe eugenics are a good idea." Militia are supposed to be a military threat: the purpose clause of the second amendment means that I should be able to buy an Abrams Main Battle Tank if I can gather up the money for it.
While logical, strictly speaking, the 2nd Amendment does not cover tanks or artillery, strictly speaking.
Is a Tank counted as a firearm?
The Second Amendment is not limited to firearms. The text of the amendment just uses the term "arms". "Arms", as commonly understood even in that period, simply means "weapons" and usually meant "weapons of the solider/warrior", and so easily covered not only firearms, but also swords, spears, knives, daggers, grenades, and, given that the Constitution, including the 2nd Amendment, has been ruled to expand with new technologies (IE, the Freedom of the Press covers mass, rapid printing machines just as much an manually set and operated printing presses in the day), this means you can make a logical argument that the 2nd applies to such things as Stun guns / tazers (in fact, this has already been said to be the case by the Supreme Court in a
unanimous decision), man-portable rocket launchers, and automatic firearms of all stripes. In the future it would also cover things like weaponized lasers or something like a Star Wars blaster.
All that said, in the case of a tank you're dealing with different things. Firstly, as it stands right now, there's not really any laws preventing you from buying any tank. A tank is just an armored vehicle at its core, and the main prohibition with tanks is that they're not road legal. However, the WEAPONS on a tank are another issue entirely. One can make a case that the machine guns fall under the category of "arms", but "arms" did not generally cover cannons or other artillery. Yes, in the 18th century they allowed the private ownership of artillery, but as far as I am aware, cannon were not considered "arms", and so technically fall outside the purview of the 2nd Amendment.
As to superpowers? Going to utterly depend on the given superpower. Wolverine's claws? Those are hardly different than a sword or dagger and so easily fall under the 2nd. MR. Fantastic's stretchy powers? Well... strictly speaking, those aren't even a weapon, so not covered under the 2nd, but covered under the right to privacy and bodily autonomy. A Green Lantern Ring, Iron Man armor, and other such things? Likely covered under the 2nd. Heat vision? Again, not so different than a weaponized laser so likely considered covered.
That said, a LOT of these would have to be considered in court cases. I expect the Marvel universe actually has a long case law concerning what superpowers are considered, since many of the powers are inherently biological, so, for instance, they would have had a case where a superpowered mugger argued in court that they couldn't be convicted of "assault with a deadly weapon" since their superpower, not being separate from their being, wouldn't count as a "weapon". Such a case would end up with the laws being modified to account for such idiosyncrasies.