How often does this occur at the BK Public Library?  Once a month?  Hardly enough to contaminate by osmosis.  Yet, enough to educate about diversity in people.

If a person doesn't like it, then don't take their kids there.  Parental Supervision encouraged.

It is NYC.  NYC is still a "melting pot" of every imaginable type of person.  Education about diversity of people is a good thing, IMHO.