Personally, I would let the mother raise the chick. Just because a hen is low in the pecking order doesn't mean they are bad mothers. At the end of the day, it's your call.
If you do raise the chick, you might want to consider getting another one. Its recommended for a chick to be raised with at least one other chick. It helps them develop social skills which I think are important. Loner chicks don't usually do well when integrated with a flock.
If you do decide to leave the chick with its mother, she'll need some assistance. I don't know the setup you have or what predators you might have but that's something to consider. I've seen mama hens gear their chicks towards safety and kill small garden snakes. If your run is secure I wouldn't worry too much about predators. Space is really important, make sure there is enough and more if possible. Multiple water trays and feeders could be used to make sure the chick and mama are getting feed. I like to feel their crop to make sure. If mama hen and her chick are getting bullied, I would just put them in a separate enclosure if possible.
I think the choice you make really depends on how good of a mother the hen is, your setup, and your ability to provide for this chick. Perhaps you could let the mother take care of the chick for a few days, maybe a week, and make your choice from there.
