Bigger issue is if diaper explodes, polymer crystals that are jelly when wet are bad for the filter.
I believe that the "swim pants" do not have these crystals, so you may need to insist on this for baby swimmers.
New moms may not know just how big those super-absorbent diapers are. Really, they can swell to something like 10x normal thickness. If that crystal leaks out, you may not see it for it is clear. When it is dry it looks like coarse salt.
From time to time we get someone visiting the forum with that problem. It clogs the filter and can even rupture a cartridge filter.
As for the pee, it won't be a whole lot, I wouldn't worry too much. Swim pants will contain any poo, and a good mom will be alert for that. Do make it clear that if poo gets in the pool it is not safe to swim and needs to be shocked.