Broody getting up and being picked on
The changed behavior that broody hens exhibit frequently cause the rest of the flock to regard them as 'strangers'.
Unless they become overly aggressive against her, I would let it go but observe closely and separate if necessary.
Grouchy is good, the whole flock respects her when she is grouchy and learn to give her wide berth. An aggressive bird might worry about this broody, and try and set some lines again.
I agree, watch, but for the most part leave her be. If you can, let the flock out to free range a bit, giving her a bit more space part of the time. They may get thin, and if it is real hot, I have coaxed them to drink a little water, but self survival if pretty well established, I am betting that she is eating.
Personally, I go down 2-3 times a week, and carefully lift her off the nest using a towel. This allows me to check and see what eggs are under her, and to make sure no one else has given her more.
I never caught any of my first 3 broodies off the nest. I just left them entirely alone, and they did things their way, and that worked too.
How did things turn out? I noticed the same thing with one of my female ducks today. I was penning them for the night. She got off the nest(that she shares with 2 other females) to get a drink. I had all 3 of my males attack her to the point they pecked her neck bald. She's back on the nest and the boys are behaving but I'm cautiously watching them. Did you found a resolve.