Was this a situation in which you were asking the candidate while everybody else either already knew the answer and was listening to the candidate think?

Or was it more like everybody was discussing (and explicitly or implicitly through discussion) admitting that they don't necessarily know the answer (while assumedly is an engineer in good standing on the team), and the group is working together to solve it?

Because both situations seem equally plausible based on what you wrote, and if it's the first one then I agree with your detractors below that it's messed up. If it's the second situation then I would have loved it and been excited to join your team.

It's very possible that the ambiguity of the situation is why there's such variance in reactions.