Itzik, I am talking more about the kids who are on the cusp, or experimenting with going off the derech. I had some friends at various parts of life like that. Most benefitted by still having their frum friends around, even if we disapproved of what they were doing. We were always clear that no, it wasnt ok to eat treif or do inappropriate things with boys or do drugs of any kind. Most came back to the fold. Some left.
I have one friend who married a guy who isnt frum. She says she still is, although I am not 100% sure (I once got an email from her timestamped on shabbos). But I would never get rid of her as a friend because of that – she is really a wonderful person, who doesnt keep all of halacha. There is no sense in “kicking her to the curb” because it wouldnt accomplish anything. I hope that when she moves back to NY in a few years, she will move back to being orthodox.
Granted, the guy you mentioned would be thrown out of my office in a heartbeat!