Originally Posted by
UAL250
Correct, the 25 min is to the end of boarding not scheduled departure. Thankfully the app is easy to use so at any point if it's looking unlikely I can just switch

Update: I made it! Flight arrived at the A gates at 5:55 and I got on board the UA flight in the high C gates at 6:08. Don't want to do that again. Thanks
Xyzzy for your advice!