There’s a couple of things that go into holding/ not holding a plane for connections.

One is the number of passengers connecting to the flight. Another is the number of connections that might be messed up on the other end. Another is gate space (is that gate needed?). Still another is FAA-mandated crew limits on duty hours. The gate attendant does not make the call to hold/no hold. There’s a team at UA that does. I did not believe UA callously “stranded” you there - there is significant cost to UA in doing so (hotel vouchers, reaccomodation on OAL, etc).

My guess is the latter (crew hours) forced UA to go, rather than wait for 15.

As for, “Travelers heading home from KOA on United via a connection beware. It is a route we shall never take again.”, a rare incident does not make it a common incident. If you want to avoid any airline that has stranded a passenger from Hawaii at a connecting point, you won’t fly to Hawaii anymore because EVERY SINGLE ONE HAS.

I’ve traveled to the mainland about monthly since 2012 from Hawaii (almost always w/ connections) and the last time I was “stranded” on a trip from Hawaii was back in 2013. If my first trip was that “stranding” trip, and if I was dumb enough to think UA was always like that, I would have lost out on what has turned out to be a very reliable airline (outside of the on-board food). I probably just jinxed myself