If it were an injured male, there is a good chance you’d be correct. One of the other males - either already in the pride, or in the area - would likely challenge and unseat him from the pride.
But, because it’s a female, especially one with cubs, it’s much less likely she’d get pushed out. The male would act to protect his cubs, and that means keeping the female around. The other females are more than likely either her sisters or half-sisters, and would similarly act to protect her.
She’ll not be able to properly hunt for the next while, but stitching her up and leaving her be is far less disruptive then moving her and her cubs off their territory, in the hopes of reintegrating them later.
Source: Ex-safari guide.