A119: Philosophically I wouldn't go that direction for a couple of reasons*, but from a rules standpoint you've basically called it. DM has discretion over what checks can be aided, and there's nothing in the rules that says otherwise with regards to monster knowledge checks.

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First, because it makes sense to me that at least one other person could help with a comment that jogs the main person's memory, and second because I think the game plays better when the players have more information. But that's just what's most fun for me.