Yeah, that would be my question, as well.
Keeping the starters in after it got much past 40-0, or 50-0, would be rather unseemly.
I'd probably pull the starters [for good] at about 40-0, and tell the second-stringers to stop the full-court press no later than about 60-0 [and maybe a lot sooner than that].
The second stringers aren’t allowed to gather game experience using their teams appropriate strategy?
This is nonsense. You don’t want this score to happen, fire the AD for putting a high school with 20 girls on your schedule.
The coach did absolutely nothing wrong.