There are some UA flights out of terminal 2, but no check-ins, so the signs tell you to go to terminal 1, which is fine, you can then easily walk to terminal 2. The signs are meant to help the lowest common denominator. A savvy traveler will know that an E/F gate means they can get off at 2 (if said traveler is already checked in). Should that be on the sign? No way. If that was on the signs, you'd have people ending up in terminal 2 who aren't already checked in. Not everyone leaving 5 and going to a domestic flight is checked in, and the tram also serves long term parking.
Thanks. That makes sense. ^ We knew after the first time to get off at terminal 1. That first time we weren't sure how far the walk was or for that matter if it was possible, considering we were riding a train from terminal to terminal.