I think they could specify rule five to disallow questions that would be answered on the first page of any search engine or on the Q&A on the relevant site, but more complex questions like this should be allowed.

But I guess it's easier to have a strict rule and look the other way/allow some posts to break it as long as no one complains, rather than to have loose/non-specific rules and constant arguments with OP+community about which side every post falls on and have to make a different judgement call for every complaint.