Getting back on topic:
In reality it is inappropriette to to talk to someone in such a manner who's so young but as I said before it's just pretend and at least in my opinion it's nothing to even find disturbing since we're dealing with a bunch of fictional characters and I would think Jim and his staff would of expected the audience just to laugh at Gonzo's silliness and not debate or question the morality of it.
I just saw it on YT and though didn't laugh I kind of smiled at it myself.
Well I can only speak for myself of course, but I agree, I didn't really think of Gonzo's behavior as "disturbing" either. Like I mentioned in a past post, I think it seems easy to see that Gonzo didn't understand that Big Bird was a boy nor a young boy at that. Plus again they didn't have Gonzo keep doing that to Big Bird in other Muppet/Sesame Street crossovers, such as Muppet Family Christmas or celebration of 30 years.
I would have to say Miss. Piggy trying to get Zac Efron brothers me a little more, there's no getting around that age difference,

. It doesn't brother me to the point where I'm not a lover of Miss. Piggy, I even just bought her book "The Diva Code."