Yesh, so having gone back and reading all the early years I missed I understand last week's comics better. Some time has passed since that party and current though, weeks or months. Sarah already did a pretty good job of kicking his ass, and Joyce didn't do so bad herself, though that was just luck and lashing out. As far as I know though, they haven't told anyone else yet about the attack other than those who knew about it that night, which didn't include Amber, or anyone who would tell Amazi-Girl. I have no doubt if she knew she'd go after him...
There's also no knowing if he even goes to the school. He was clearly and deliberately targeting Joyce and knew what to say to her. To me that means he's probably raped other girls before. The guy who threw the party said he has seen him at parties before, but not that he knew him. It's possible he doesn't even go to college, or goes somewhere else, but hunts for targets at college parties, especially ones with freshmen attending, as they're likely to be the easiest targets.