Sorry, then you are functionally ignorant of the very foundations of western civilization and the American Ideal.
Private property rights and freedom of association are at the fundamental root of a free society. Someone is free to be biggotted against someone else for whatever reason they choose, don’t have to like it, but that’s reality.
A private club certainly has every right to decide who may be members and who can or cannot use its property, its really no more complicated than that. You may not like their decisions, but your desires have absolutely no right to have any influence on theirs.
If some private club says hey, no Jews, no Muslims, no Gays, No wasps, no Blacks, no Asians, no Hispanics, no Whites, no people with piercings, no people with vestigial nipples.... or whatever, that’s their right. Individuals are free to associate with whoever they want, and not associate with whoever they want and you nor the government, nor anyone else has any right to tell them otherwise.
A business or public accomidation fine, but a private club? Absolutely has every right to admit or deny whoever the hell they want for whatever reason they want.
The steam coming from your ears has clouded your thinking
If they had such a rule, and I don’t think anybody has said they did, why did they rent out their facilities to a black day-care center without stipulating that no blacks were allowed?
Since we have very little information, I’m going to GUESS that 1st, they had no idea the group would bring 60 kids — maybe the agreement specified fewer, or maybe they just didn’t check. Second, I bet the kids did behave in a manner that was not appropriate for the pool, and that could be the reason they are trying to revoke their rent.
Or it could be that the club just didn’t know how many racist democrats were members, and once their racist democrat members complained about how they elected politicians to pay off all the blacks so that they wouldn’t have to swim with them, the club decided they didn’t want to lose all their racist demcorat members so they are trying to screw the inner-city kids just like the democrats do all the time.