I understand why he's beating himself up but I don't agree with it. It's true his kindness wasn't truly genuine. He probably took her in cuz she was cute and that's fine. No human on this earth is truly kind, we all do nice gestures that have ulterior motives. Either it being gaining satisfaction from doing the good deed or having someone indebted to you. Every action we do has a motive behind it. It's normal and a part of our psyche.
If he was a true piece o' shit, he would've banged her and left her for the next degen to use. Instead he gave her a place to stay and a father figure to lean on. Nothing wrong with that morally.