These shorts would be restrictive when the girls roll or slide on the floor. The girls know that these might slide off if they try to slide like a seal and pancake a ball. They also know that they would be immodest if they do a roll, so they might be unlikely to actually do the roll that they need to do.
Spandex has been around for many, many years. It's not evil, it's practical.
If it's an issue for someone, then they can approach the coach. If the coach wants spandex cause it is better for the game, then the girl has a hard choice to make. It won't be the first or last hard choice to be made in that life.