They were very upset. [Prefect interjects, a little defensively, because being upset is a good excuse for doing stupid things, then a thought occurs to him, and he gives Scrad and Charlie a sidelong look.]

But you did sort of think, Comrades. You did know that this wasn't going to work, you just couldn't think of anything else to do. [Yeah, he heard you talking to Arkady. And a bunch of other people. HE KNOWS YOU KNEW.] You shouldn't just do things and then act like it's because you weren't smart enough not to do them. You're not idiots.

[This might not be entirely true, but they clearly need the self esteem, so Prefect'll take a risk and force himself to believe it.]