Could you elaborate on how the "average republican sentiment has changed significantly since bush"? Not saying it hasn't I just don't understand how it has.
My main point was that trump announced this to provoke violent groups into violent actions. This in turn will likely lead to him having a 9/11 moment where he can boost his popularity as he can act like a tough leader.
At best, trump does these irrational things for attention. Which I suppose is infinitely worse.