Originally Posted by sgn1k

I agree that this rule does appear in writing and is therefore "valid", but it still constitutes cheating, whether or not that's its purpose.

First of all, let's look at what UAL states in its guide to Mileage Plus, right inside the front cover: "Fly United and you earn 100% of your actual flight miles with a 500-mile minimum." I cannot accept that a reasonable person would interpret "actual flight miles" to mean anything other than what it means in English: actual miles flown (BIS). To pretend that it means "what the actual flight miles would have been if we had actually flown you directly from your origin and destination, which we didn't" is sophistry.