Sarcasm is an adjusted stress reaction.

That last scene did seem awfully Master like. I wonder if the Doctor put them in there or the High Council did. My current theory is the High Council did and told the Doctor if the Master got out again, they'd kill the Master for realz this time. And then the Doctor promises all parties involved that he'll stay and play jailer. Husband pointed out this is an imperfect but in the long run more effective prison for the Doctor than most other attempts to hold him. So the High Council gets two renegades taken out of the big picture for the price of one.

And the Doctor means well, of course, but is simultaneously co-dependent and inconsistent. Par for the course, then, especially where the Master is concerned.