If you were/are a teacher, how would you deal with a kid like this? Would you punish him?

She should have done more than just ignore his absences. She should have done something to get him into more challenging classes - maybe not in math, if those weren't available, but he should have been in school and learning something worthwhile during the school day, not using the time here as a vacation. I'm sure his parents wouldn't have been pleased to know that he skipped class and spent the entire year just chasing girls, but neither should he have been forced to sit in a class which was well below his abilities.