While the "PC culture" in the campus indeed has its issues with intolerance and what not, I have my doubt that those working class voters in the rust belt and rural voters across the country were motivated to vote Trump because of the college PC cultre. My hunch is that they are not even aware of what those controversial incidents in the college were, just like majority of Americans who do not care much about what happens in college campuses. Interesting in this regard is that Trump himself rarely told his audience exactly what "PC" even means. He simply repeated "Political Correctness is killing us!" without what the real world examples of PC were. Angry folks project and denounce anything that pisses them off as PC.
Same goes for the extremist Muslim terrorism. Those rural/rust belt voters live in remarkably homogenous environments. It is unlikely they interact in day-to-day lives with a person of Muslim faith who subscribe to its radical sectarian ideologies. Could it, nonetheless, scare them? Of course. But mostly because of the fanning of Trump and Alt-right, the latter of which has kept pushing false and exaggerated narratives of what is happening in Europe. Domestically we do not even know the exact motive of the Pulse nightclub shooter. Maher beef is a much more liberal one in that he views many of Islam's doctrines incompatible with liberal democracy. (e.g. misogyny) The Trump voters are much more scared of so-called "Sharia Law" being imposed on U.S. citizenry, thanks again to Alt-Right and Trumpian propaganda.
Maher is wrong on both counts. Ask a Trump voter what they think PC means. More often than not you will hear generic rants against the liberals and the lefties. It is not what Maher thinks it is. They might find more common ground in rejecting radical Islamic terrorism, but they get there from very different originating places.
Edit: I missed the last paragraph, where he says:
"Democrats have become to a lot of Americans a boutique party of fake outrage and social engineering and they're not entirely wrong about that,"
That is a credible argument. Maybe I misunderstood the first part of his diagnosis as well. It is a reasonable argument that the liberals neglected the working class voters. But I do not think these voters had a particular animosity against PC. It is a liberal fantasy to think these voters cared about a lunatic PC warrior crying about someone else's Holloween costume.