Do you have any older address posted except that from stake btc address thread?
No, because I have bought it from the original owner outside of this forum and he has not never posted any his bitcoin address in this forum.
That thread is very new. I don't think receiving a signed message from an address posted in that thread would do very much to prove ownership.
How did you know the previous owner actually owned the account when you purchased it from him?
Yes, even I feel the same..
If you aren't able to provide a signed message from an older post no one would even pay 0.1 for this