I think there's a chance a moderator will allow you to send a small amount of BTC from your address to one owned by him to confirm the ownership, but this will surely fall into a lower priority than unlocking the accounts that can sign a message.
Unfortunately, you are unable to read despite this thread having only 3 posts before yours. I literally stated in the above post that coinbase uses a communal wallet to send coins, rather than attach both txinputs and txoutputs to a single address owned by a user.