When I was 98789 I staked one of my bitcoin addresses, but unfortunately it was a Coinbase address. To the best of my knowledge, they removed the ability to sign messages years ago, so while I know that that is the gold standard to prove you are who you claim to be, I won't be able to provide a signed message for that reason. I see no reason why I would claim some really old account (that has been inactive since then and that does not belong to some community "hero") to be me, but as alternatives to prove that I am 98789 I could tweet whatever message you want from @tregaus4 (a crypto/fake X account that belongs to me, as you can see in this unedited message from 98789 (
https://bitcointalk.org/index.php?topic=1310101.msg13471129#msg13471129)) or if someone with more privileges is interested in verifying my claim, I can somehow confirm via email.
Tehnically, tg9 is the alt account of 98789 so you should log into your main account, tag the new one with neutral and then you can put the old back to rest if you wish and continue with new one.
Everything is somehow confusing. Was your account hacked or sold?
From what I understand, neither. He just don't want to log with the old one, for whatever reason.