About 10 days.+/-
Just put him back in before the hens peck his brains out.
That's 8 days or less. Don't anthropomorphize quail.
"Being mean to a human" may be fine for a quail.
It can be hard to watch, so I don't.
Plucked feathers, and a little blood are fine.
A 1m to 4f will find a pecking order. removing one or the other is not advised.
As long as there isn't serious damage to roo or hens, then they are doing it right.
Banish the roo for 8 or more days, then try to put him back with the hens, then you have a "Kill the Roo" contest. It happens!
Put the roo back with the hens, and let nature take it's course.