Well, 'dude', that was a defining point of Roman, Carthaginian, Barbary states, Hunnish, Mongol, early Turkish, and countless other slave-owning cultures, as well as in today's slave market (we live in the Golden Era of slave trade, after all. Of course, now it is 'human trafficking'.).
Let's face it: your GM nerfed your situation to prevent bad things from happening to a PC. That's OK, there's no wrong way to play the same when you're not at my table, but what it means is that surrender was a safe option for your PC. As you said: you knew you would be rescued, and nothing bad would happen to your PC.
But that 'safe place' type of gaming is not universal, and if a GM is playing a level field, your confidence would be badly misplaced.