Originally Posted by
gfowler-ord-1k
It is spelled out in the T&C,
bolding mine. I dont think it is fair either, but they make the rules of the promo. Our job is to find the loopholes in it

Roundtrip is required. A roundtrip is defined as travel from an origin city to a destination city with return travel beginning in the outbound destination city back to the first origin city with all segments on United, United Express or Ted. Open jaw and circle trips do not qualify.
I think one should appeal to UA MP and marketing. The person who wrote the code may not know what a co-terminal is.
Thanks for the clarification. I'm wondering if they've accidentally DQ'd any LGA-XXX-JFK's since that is the same city - just not the same airport...