The more we learn about Rym and the pactrids, the more there is to admire. They seem to be a more tolerant and civilized society than the humans. The government Callum is living under must be particularly vile to kill envoys.
There are a number of things Callum should deduce from what he was shown. The humans are the aggressors here and liars. There is virtually no way for him to expect to both escape and get home on his own. Finally, the pactrids don't have to torture to find out what they need to know.
Now, is he smart enough to come to these conclusions?