I don’t doubt you’ve heard someone argue that, but I never have. I’ve always heard it as a right to defense, generally as in a right to defend yourself from oppressive authorities. I never took that to mean assassinations as much as militia actions against militaries.

You can argue whether or not that is an effective approach to securing freedom, but that’s the argument I’m most familiar with.

The 2A people couch it in metaphor and implication, but "we need guns to stop tyranny" is fundamentally saying that tyrants ought be shot. We can argue whether the semantics of whether death in battle counts as murder, but I think that's just quibbling over the definition of "assassination".

More of a distinction without a difference. Once you get to that situation, you've legitimized murder; now we see what that looks like.

"Militia" action against "military"? Neither side will bother with the scruples of waiting for the enemy to put on a uniform and pick up a weapon. It will be death squads vs car bombs.