Staring at someone for an entire trip (assuming the trip wasn't only a few minutes) is pretty creepy. I can't fault the lady for not talking to the guy. For all she knows he is some serial killer - he certainly was acting strangely enough. I don't think it's unreasonable for people to expect they should be able to travel without being stared at.
It might be a mistake to think his staring was sexual though. Maybe he liked her cloths or thought she would look good in his freezer. You never know about people.