Where would it state that parents could not watch a practice? This is not normal.
I've heard of some HS coaches in other sports banning parents from practice, because sports parents can be pretty awful. (I've had to lay down some stringent rules for parents at hockey practices before.) Any (sports) program could probably put it in their code of conduct, but I would see it as a significant red flag, even if you had a team with a high coach/player ratio and lots of very involved and very background checked adults.
(My dad frequently *chose* not to attend our practices, but he was never actively forbidden from doing so.)
Several of the USAS teams in the DC area ban parents from the deck during practice. If the facility has a viewing area that overlooks the pool, parents can watch from there, but if the facility doesn't have one then the parents are just unable to watch.
On the USAS team I coach, parents are allowed to sit in the stands, but are encouraged to watch from upstairs.
