Would Trump moderate his insane “policies” once elected? I don’t know, but I’d say that electing someone who promises to ignore the rule of law, in the hope that they don’t really mean it, has one of the worst track records of any idea in human history.
I think people support Trump for the same reason why second-graders support the class clown who calls the teacher a fart-brain to her face. It’s not that the class literally agrees that the teacher’s cranium is filled with intestinal gases, or considers that an important question to raise. It’s simply that the clown had the guts to stand up to this scolding authority figure who presumes to tell the class every day what they are and aren’t allowed to think. (As far as I can tell, this has also been the central operating principle of right-wing shock artists over the decades, from Rush Limbaugh to Ann Coulter to Milo Yiannopoulos.)
The truth is, there’s a movement that’s very effectively wielded social media to remake the public face of progressive activism—to the point where today, progressivism could strike an outside observer as being less about stopping climate change, raising the minimum wage, or investing in public transit than simply about ruining the lives of Brendan Eich and Matt Taylor and Tim Hunt and Erika Christakis and Dongle Guy and Elevator Guy and anyone else who tells the wrong joke, wears the wrong shirt, or sends the wrong email. It strikes me that this movement never understood the extent to which progressive social values were already winning, with no need for this sort of vindictiveness. It’s insisted instead on treating its vanquished culture-war enemies as shortsightedly as the Allies treated the Germans at Versailles.
So yes, I do think that the bullying wing of the social-justice left bears at least some minor, indirect responsibility for the rise of Trump. If you demonstrate enough times that even people who are trying to be decent will still get fired, jeered at, and publicly shamed over the tiniest ideological misstep, then eventually some of those who you’ve frightened might turn toward a demagogue who’s incapable of shame.