Post History

It's a balance.

On one had, we want to be a store of knowledge.  It doesn't matter what prompted a particular piece of information to be posted if it serves the long term purpose.  We also don't want volunteers that wrote answers in good faith feel like they wasted their time because the original asker turned out to be fake.

On the other hand, we certainly don't want to encourage people creating fake accounts.  Not getting the desired result is one way to avoid encouraging such users.

Deleting the offending user is an obvious thing to do, and was done in this case.  That leaves the question of what to do with the content that resulted from that user's actions.  In this case, since an answer had already been written and there was some discussion in comments, I left the question and answer.  In other cases where there was no answer, I deleted the whole question.

I admit I'm somewhat on the fence about deleting the whole question in more cases myself.