I know other people believe it isn't a big deal, but come on. Nick should know what they're showing to innocent kids, why make a dumb ::dolphin noise:: decision like that. And yes, it is a big deal. If a parent saw this, of course they would be pissed.
"Oh, but its just a frame of a cartoon that lasts for a second. EH! Parents are so stupid nowadays, 90s were better"
So? It's still inappropriate. Any kid could have seen that and paused and asked their mother what it was, and the mom bashes her fist into the television screen and gave Nick a call.
They know it's inappropriate, so why risk it? You could save yourself a lawsuit. And even if the executives/screen editors didn't notice, that's their ::dolphin noise:: job!
Yeah, the parents may be crazy and overprotective of their kids precious eyes, but if the censors know that its gonna raise some heckish controversy, then they better do something about it than rather sit there and "wait... see what happens."