No. Stockfish owns the copyright to their code. You can't copy stockfish code without a license from stockfish. There's no provision in the GPL for some third party to re-grant a GPL license to someone else after their license was terminated.

Don't think it's a problem to give them the code, as long as your own license isn't terminated.

But it would be a breach of copyright for Chessbase to distribute or modify the code, after their license has been terminated.