I think the theory of those who believe he was trying to do the right thing is that he foresaw a situation where if he didn't act, the result would be roughly e

I think the theory of those who believe he was trying to do the right thing is that he foresaw a situation where if he didn't act, the result would be roughly equivalent to a much worse violation of said norm - and so he chose to preserve as much of the spirit of the norm as he could at the expense of participating in the violation of the letter. Whether this theory seems correct, and whether it argues for principled or unprincipled, I suspect will have varying answers depending on who you ask.