Rank speculation to fit your premise, Chuck. C'mon - you're way to smart
for that.

At the point where the guy was reprimanded by the flight crew and calmed down,
the "security" issue was extinguished. Something p'd off the pilot enough to
divert the plane and have the guy arrested. Is this a normal response any time
somebody gets drunk on an airplane, discusses politics with a seat mate, and
touches the knee of the person sitting next to him?

I suspect the pilot wanted to punish the drunk for his views, not his
inebriated behavior.