As an example...

goalie-parents are finally flying home PBI-IAD-SFO tomorrow (May, 13th) after pushing their trip from April 15th. The equipment on the only non-stop IAD-SFO is a 319. If goalie-parents are notified that their IAD-SFO flight is more than 70% full and want to take a different flight to fly home, the only non-stop option IAD SFO is the same flight on subsequent days but the small equipment still exists and they could still be met with the same problem the next day, the day after that, the day after that and so on...

My solution: Just fly a larger aircraft and actually block and not sell middle seats. Yes, it might not be economically efficient for UA but UA needs to suck it up during these trying times the same as many of us are

*goalie-parents were originally non-stop FLL-SFO and that got axed and the best option was via IAD (n.b. they are not flying via EWR or IAH as that is, imho, not COVID-smart)