Probably depends on whether the entity baiting you is the same as (or represents) the entity you're ultimately purchasing from. If the aggregator is merely redirecting you to the airline and getting a kickback, as opposed to actually being a middleman, maybe that's a loophole in bait-and-switch law?

On the other hand, since GP furnished payment details to the baiter, I guess it really is a middleman, in which case you're absolutely correct.