Unfortunately I'm not in a good position to answer that as I rarely (maybe 1x/year) end up flying out that late. I have had last flights out cancelled out of other airports on other airlines so I'm definitely not going to say it "won't/can't" happen.

We're supposed to be getting scattered t-storms today/tonight & tomorrow. Wx delays last night were supposedly up to 3 hours. He's definitely better off if he can try to get out on an earlier-scheduled flight.