I think he lost me when he came down the escalator, said a bunch of racist stuff, and started talking about building a Wall that Mexico would pay for.
I didn't give a fuck about this at all. I don't care if he builds a wall or not. I don't care who pays for it, so long as it's not the UK.

the Mexico-paying part sounded really, really dumb.
Sounded to me like he was trying to appeal to his voters in the South. And it sounded to me like he meant they would pay for it economically, not by writing out a cheque.

Muslim ban didn't exactly strike me as a wise step either, given most terrorist acts...
You may find this surprising, but people who oppose Islamic immigration do not tend to oppose it based on fear of terrorism. It's usually based on the nature of the religion, the way they treat women and homosexuals, and perhaps a fear of their culture replacing ours over a long period of time.

the welcoming of immigrants and diversity
You should run for Mayor of London.

which made me think it was not an expression of the majority's will.
How ironic that the "majority's will" is an important factor in your position here. You know what I'm getting at here, don't you?