I fail to see how Stockfish is being childish here. Sounds like ChessBase was given ample opportunity to comply (release the actual source) and tried to weasel out of it (by releasing a modified copy of their new engine's source which hides the secret sauce). Even so, Stockfish only tried to revoke the license when they came to find out ChessBase had ignored the GPL requirements of Stockfish with not one, but two of the engines they sell.
How far should you let someone fuck around with your license terms before you decide to exercise the nuclear option?