There's really no conflict in the examples cited.

The right to keep and bear arms is in the Constitution, with the minor problem of being stated in archaic language that hasn't been interpreted "in modern words" so that wingnuts can understand what it means. That the states cannot violate the Constitution is pretty well established. The business of telling us what the Constitution means is one of the things the SCOTUS is supposed to do.

The Constitution doesn't mention health insurance, so "states rights" can prevail, subject to the usual extortion of withholding "Federal funding" for failing to comply with unrelated pograms (not giving back money the fed shouldn't have taken from us in the first place) from those states that don't go along.

The question nobody seems able to ask is whether the Fed has the right/authority to establish a funding program to assist state projects - projects the states "must do" - and then to impose unrelated conditions as a requirement for participation in "sucking the big teat" - which is how they've "mandated" a vast number of nation wide requirements that arguably should have been left to the option of the states.

John