Honestly, I believe holding adults to things they said as a teenager is quite silly. The brain development stops at the age of 26 and maturity and ignorance is something very questionable among all teenagers - adults aren't even fully developed let alone teens. I would hope people would support change and realize that the things we say as teenagers often do not reflect who we are now or what we believe is right or wrong.
I have seen many times in the KPop world where people pick these adults apart because of a mistake made when they were young. They are mistakes, and they have and will keep learning from them. I can't even remember all of the dumb things I said when I was younger that in this day if I was popular would've been 'cancelled' for. I don't think anyone is exempt from this honestly. I just hope that he has realized his mistake, and if it is brought to light to him that he may issue an apology. Taking accountability for your actions as a youngster is good, however, with how the culture is today many will probably say his apology wasn't enough or sincere.