Exactly. They've been screeching about this decades before Trump, insisting the US is some Christian fascist paradise being besieged by an international cabal of communists. Every Trumpite politician I see yammers on about "the left" in every negative thing that happens. Trump didn't need to get shot at for them to start marching with torches at Charlottesville, or to start attacking city infrastructure to target minorities, or to push state governments and courts to adopt more and more aggressive reactionary legislation. Yes, this will be their rallying cry, their "proof", but with how much pressure reactionaries have been putting on citizens, it was only a matter of time until someone pushed back and gave them the excuse they wanted.