22 year old son getting a vasectomy

My son is on his last year of college and had an awful spring semester. He has a female friend who wanted to date him and my son has always been in a weird place when it came to his sexuality or idea of relationships. He declined. They stayed friends. Then they went out to a party and he woke up in bed with her. He found out a few weeks later that she slipped something in his drink. Me and him talked about it and I told him to report it. He didn't think anything would come of it. A month or so later she told him she was pregnant. Even if he went to court about the assault he still would have been hooked for child support. He started self harming and it put him through a lot. Luckily she miscarried. I know that sounds bad but I don't want any grandchildren born my rape. He is seeing a therapist at his university and told me he's getting a vasectomy in case it happens again and then at least he won't get them pregnant. He said he will just adopt kids in the future. I think this is really impulsive. I'm not downplaying his trauma but I feel the chances of this happening again aren't super high. I think he's just not well mentally and being impulsive.