But you say he's just a friend...

Question...Is it okay to have your child around "friends" of the opposite sex? Now in this case I mean a true friend, someone whose company you enjoy. Not a friend with benefits or a friend that's really a significant other, but you don't have "titles". I mean a 100% platonic almost a sibling kind of friend. Now that that's clear let me give a bit more context to the question. John and Sue have a son. The son lives with Sue and John gets him from time to time. On one particular occasion when John was bringing the son home, Sue had an old friend over that had just stopped by when he was in the neighborhood. John was cordial during the exchange, but later had a few choice words for Sue regarding having his son around "random negros". Sue tried to explain it wasn't like that he was just a friend and nothing more so it shouldn't be a big deal. But it was for John.

Now, if you have a child and are no longer involved with the other person it’s expected that you both will have all types of friends. Most females I know have huge problems with a guy having their child around "random women" and clearly guys have the same feeling about "random men". But I think this is more in the context of romantic friends. We all have friends of the opposite sex so is it ever ok to have your kid(s) around them? Or should you never have your child around anyone of the opposite sex? Is your co parent justified in getting upset if he/she finds out a friend has been with you when you had the kid(s)? Was Sue out of line or is John just being petty?