Given today's standards, its to believe the account was banned for trolling, but if memory serves I did receive a temp ban for such a thing once in 2014. For reference, user proudhon has been trolling the WO thread for the better part of a decade 
You might also see if you still have access to your old Ripple addresses; signing a message with one of those would work equally well. Seems like you used this one a few times:
You guys are incredibly responsive. I might try to sign a transaction with the key that allowed me to donate 5 BTC to Bitcointalk. But that goes way back. It doesn't seem simple to me!
You might also see if you still have access to your old Ripple addresses; signing a message with one of those would work equally well. Seems like you used this one a few times:
rGd4FaNjg22EvTuot3SRKF1suueUSc8Lhd