The Watcher:
The original question on Dear Abby had to do with a daughter writing in about the fact her boyfriend, whom she just met during her first at college, was going with her to meet her parents over (I believe) summer break. She wanted to sleep in the same room as her boyfriend during the visit, which her father wasn't happy with.
I'm assuming, based on the context, that Bob would have a problem with his unwed daughter sleeping with her boyfriend in his house.
The fact that he should not have an issue with this does not mean that he doesn't have every right to withdraw his financial support of his daughter over it. It's stupid, but I have no problem with parents instituting "My money, my rules" with their adult children and following through with it.
Also, I'm not sure why you're so hung up about what he said about the boyfriend paying for everything. While it's insulting that he assumes she'd need a man to financially support her (or not, seeing as, if he’s paying for everything now, she obviously does need someone to support her), I doubt he meant it any differently than if he'd said "You can start taking care of yourself and pay for all the stuff you need". He’s pointing out what is going to be the consequences of her actions, not what he thinks is the reality of her financial situation just because she’s having sex.
Basically, I think your reading what he wrote waaaay too literally. Just because he wrote “You’re boyfriend can start paying for everything” doesn’t mean he actually thinks her boyfriend can or should support her.