The GA is a ding dong for making up the story. As for the policy, the GA may or may not have been following orders.

Overall, I think it's a failure of the system to not recognize that 26 passengers were about to misconnect. Sure, they were supposed to be there 15 minutes prior to departure and "be ready to board" but the stated goal is to close the gate door 10 minutes prior.

For the process to incur the ire of 26 misconnected passengers instead of keeping the door open until that 10-min threshold, or not determining that this is one delay worth getting on the books, is shortsighted and stupid.