This is an illegitimate argument in the context of Second Amendment. The "second amendment people" are pretty vocal proponents of strict adherence to the US constitution - hence the name of the group.

Whatever reasons Trump was voted in for, second amendment people should insist on him following the constitution. He's not. That's not even arguable on rhetorical grounds. Trump regularly defies court orders, spends money on things not authorized by Congress, and impounds money allocated by Congress. That behavior is the constitutional definition of tyranny. Therefore second amendment people should be at least metaphorically, if not literally, up in arms about him.

Again inarguably, they are not. Therefore their self proclaimed basis is a lie. They are just blowhards and we should disarm them ASAP. They have no sound reason for existing as an armed group.