Now would you have been steaming mad if they would have put you on the plane and your checked luggage not made the connection??
You do not state if you had carry-on luggage (ok ok I know PLTs always do carryon) .. but would you have been more happy to get on the flight and KNOW your luggage would not have made it??
Been there done that. STL-JFK then JFK-BDA. Arrived in JFK late (ground taxi delays). Flight was across the corridor .. ran off the plane and tried to board the connecting flight. Told it was closed (door closed tho still at gate with jetbridge in place).
The gate HAPPILY gave several of us (business class pax) hotel and meal vouchers.
They had known we would not make the flight and thus boarded standby pax. Bet your flight was full also .. and they looked at the arrival information in your reservation and decided you would mis-connect.
Yea you did things right. You were destined to not make the connection. The Gate Agent could have cared less that you were 1 or 5 pax . that you were PLT or non-tier .. that you were full fare or award tickets. They felt you would miss the flight and boarded it accordingly.
If you are so very demanding that you insist the Gate pull people off the flight .. I hope you enjoy UA.