I'm just correcting your original clam that tanks are not legal to own by posting proof that vehicles defined as tanks are not illegal to own. No need for you to move the goal post by saying these kinda tanks are legal because....
It’s not moving goalposts. It’s common sense.
Just like you can’t own a live land mine.
Or, I don’t know, a grenade.
The point is, there are weapons we have decided are not needed/allowed at the civilian level. At least not without some level of regulation. Often HEAVY regulation.
At its most extreme level, it’s why Billy Bob doesn’t get to own a nuclear weapon.
The actual example does not matter.
That’s semantics. We are talking about drawing a line.