You can prove you own the account by signing a message with that address.
Unless Theymos and Cyrus make an exception for you to recover this account , you have no chance.
I read somewhere "mprep" saying Theymos did not give any guidelines for staked ETH address for taking as valid proof.
It is bitcoin forum, Theymos will ask for bitcoin staked address only.
Might your proof /validity may help in DT to tag that account.