~320 hours isn't an uncommon amount to bank, I had more than that when I left my first tech job after 2 years. Albeit I didn't just take time off at the end I went the payout route but that's not really an option for unlimited PTO. I also took over a month off at the end of every year at then next job as they had decent total time off but didn't allow it to be rolled over year to year so I wouldn't say taking a month or two off is ridiculous in it's own right either.

Hard to say if it was actually unfair or not given the lack of background details (e.g. were they only there for a couple of months working the minimum needed or where they there for 2 years working heavily) but nothing about what was said so far actually seems unfair. "unlimited pto" should be about flexibility not about trying to silently lower the amount of PTO people take.

My current place now is much smaller and has unlimited PTO. I just act like it is no rollover front loaded and arranged my major blocks throughout the year up front. Throughout the year I'll make additional minor requests for unplanned things. Unfortunately many others don't do this and even though nobody is ever denied very few come close to using how much I get approved on Jan 1 and they'll just leave without it.