The alarm gave him something to focus on, something that he could hold on to. It meant that help was coming ... but given who they were dealing with, that was as much of a concern as a relief. Whoever was coming to their rescue had better be careful, and even then they might need help. He couldn't do much, not in his state. Focusing on the task at hand was a big enough challenge, he wasn't up for a fight. But that gave him an idea ...

Superman's struggling slowed, eventually stopping, and he went limp in his restraints again, and for all the world it looks like he had passed out again. Slade was expecting him to be completely helpless. Why not play the part for a little while?