In Bread and Circuses why did Merik wait until the last minute to transport them back to the Enterprise?

This question is about Bread and Circuses in the original Star Trek. What caused Merik to use the communicator to instruct the Enterprise to beam up Kirk, Bones and Spock when he did? Since he was weak and the Procounsel wanted them to stay, he didn't try to rescue them at first but gradually he felt bad and wanted to help them. Still though, Kirk should have been executed by the time Merik finally did transport them back (Scotty disrupted the execution by knocking out the power source, to which Merik had no knowledge of). I think Merik had stole the communicator before Kirk went on stage for the execution. What did Merik intend to do with it? Did for some reason he only wanted to save Spock and Bones but not Kirk?

Also one last thing. They had a condition green for when they were in danger but did not want anything done about. It sure would seem likely they had a code word for when they did want to be transported out covertly or otherwise require covert assistance. Why didn't Kirk use it?

I'm very surprised this episode received as high ratings as it did.