Precisely. I was referring to the reason given for the initial delay. There had been no plane swap, the plane had arrived 3 minutes early, and boarding was begun 40 minutes before scheduled push-back. Hence, BS. The final reason given was something like "operational difficulties affecting our operations", which seems to cover just about anything!

And while I think the whole discussion of the "science" of calculating weight has been fascinating, my real question was why United didn't know they were at their weight limit before boarding the 6 stand-bys. It was after push time, so presumably these calculations had been done, but apparently not. The whole episode had a bit of a clown car aspect to it (just a short wait so we can get them on; no, now just a short wait so we can get them off), hence my original title referencing an unforced error, which was edited by the mods...