You should also send an email to the
recovery team with one of those signed messages. Just a thread in meta might not be sufficient
Hope it works out for the best

As far as I can tell, the recovery team only works for people that have lost access (passwrod mostly) to their accounts. A ban for plagiarism is in other whole level and I pretty much doubt the team can do something about it.
you're right! this probably went down in the process of the thread. in principle, you have already laid the right track yesterday!
You could also export the private key (same tab, but private key instead of sign) and sign it on electrum (for example).
Not really, as it turned out that blockchain only lets you sign or get the private key of imported addresses