In neither case the government was/is legitimized by a fair election.
In both cases the dictatorship had unfolded long ago.
If G.W.Bush had installed a family-member as his "rightfully-elected" successor, there would have been civil war, 2nd amendment or not.
You don't need a legitimization to fight the illegitimate. The above interpretation of the 2nd amendment just sows distrust and provides a quasi-legal excuse for armed insurrection whenever you feel like.
Not moral excuse.