Legal terms and such can be really confusing so just to clarify --
"Illegal" typically has to do with Criminal Law, with consequences like jail and such. Framing another site without permission typically has to do with Civil Law, specifically copyrights, and possibly trademarks (those two areas, plus patents, are the trio known as "Intellectual Property").
Confused yet?:) Sorry.
Suffice it to say that guessing at or supposing about Things Legal can be risky because qualified legal opinions are based on specific facts and applicable laws.
For example, in copyright law, whether or not there's any commercial intent/benefit is just one of a number of legal puzzle pieces to consider because copyright infringement can occur whether or not the unauthorized framing is commercially oriented.
Hooboy. Not any clearer?
Okay, here's the deal:
If the original poster, or anyone, ever wants or needs a reliable legal opinion, they should consult a lawyer, not a message board.
(Oh, and using someone else's stuff without permission, for any reason, is typically a bad idea:)