Perverts only stalk in parks? If anything, this is a "feeeeeel good" ordinance.
When cops confronted them, arrested them, etc. the ACLU and NAMBLA launched lawsuits against the city because there were no state laws regarding public parks unlike the other venues I mentioned.
So the city was forced to institute this rule for public parks in order to bar pedophiles from them.
If the ACLU can get enough examples of childless adults hanging out in public parks, they can sue the city for civil rights violations regarding selective enforcement.