Really I can honestly say my analytical approach to this being a complete dangerous cult had zero to do with college. College doesn't make critical thinkers, but it does work well for them.
I think the constant encouragement to apply critical thinking skills in college can subtly help wake up a JW. I agree that if someone's going to learn critical thinking, they're probably going to have it worked out before college, but when you're in an environment full of people questioning things, it can drive you to apply it elsewhere. I'm sure it had some degree of an impact on me - when I was in college was when I essentially became an atheist struggling to remain religious due to the phobia indoctrination.
I hadn't thought about the idea that keeping people from getting good jobs makes them less likely to find good association outside the cult, but that makes perfect sense. I've seen it in my wife too - when she worked it was always around uneducated people and most of them were lazy and directionless and it's easy to get the idea that "this is just how worldly people are."
Another element of college (especially when living on campus) that plays a huge factor is that it takes one out of the parentally-controlled routine. That routine supports the cult and makes it easier to stay indoctrinated, and challenging it can give someone the breathing room they need to wake up. The exposure to a diverse group of people from different backgrounds, often with pressure to be accepting of people's differences, also can make someone realize that there are good people out there that have valid reasons for not being a cultist and you know will never join up - makes you question the cult doctrine about non-JWs dying at armageddon.