It just seems to be locked due to inactivity/being possibly compromised. If you can sign a message it can be unlocked.
Odd, I found messages from 2013 in the Staff section asking for his ban for trolling.
But the "locked_2019_vuhnu" email might indicate that it's not a ban. But he said himself that he was trolling
Maybe it was just a temp ban. You're unlikely to get permabanned for trolling unless you've had multiple warnings and bans and still won't stop.
Edit. It seems there is actually two bans on the account. The other is for "Alt currencies content outside of Alt currencies board" which doesn't have an expiration date. Maybe one was forgotten to be put in because that also is unlikely to get you a permaban unless you're a serial repeat offender. Either way, op is going to have to sign a message if he wants the account unlocking.