If he is a shy nerdy guy, is this normal?

Have you tried talking to her? You're in college, you're adults and there's hopefully some maturity that comes with that. Let her know you're not trying to step on her toes, but you and this guy get along very well together and you just wanted to let her know before she saw you together. There's no reason you should have to hide in college. Everyone can be reasoned with. If she's honestly that horrible and won't accept it, then he should consider her a stalker and contact the police if she acts out against him.