In fact, you just worsen your situation by acknowledging your mistake to others in which people would ultimately put more neutral trust to your account.
He didn't. Acknowledging in this case is much better than lie. If he'd lied and said that he didn't and lovesmayfamilis then
showed that he even didn't remove all his AI posts before that, he'd probably get a negative tag. He didn't lie and so he didn't make the situation much worse.
Now he has two neutral tags. If he will never use AI anymore, if he'll leave good and informative posts, get a positive reputation, then one day campaign managers will suppose that old days events are no more actual and neutral tag will no more mean anything not depending on if it will stay or will be removed.
So acknowledging is a first step for better situation.