I'm going to wait for some more PC posts, I'm not sure what to do. I think fighting 3 pit ghouls is pretty much certain death, especially in our current situation.
Cavaliers aren't like lawful good, protecting all that is good and decent, they are glory hounds. At least that's my understanding of them. So I'm not sure if Thak only did that to live up to the perceived cavalier requirements, or was intentionally doing it regardless.
If I could forecast this, I think Thak's dead and the rest of us have to try to figure out how to stay alive by either fleeing or some smooth talking.