It may not be "intolerant," but it may be highly counterproductive if you go about it the wrong way. The reason why "fundamentalist Christian" has such a bad connotation for the general public is because all too often, self-professed "fundamentalist Christians" are so very unpleasant, and so very self-righteous.
One doesn't get much mileage out of "pointing out sin" when the first response of their audience is a visceral dislike.
Mr. Rogers knew that. His approach was simple in concept (and difficult in practice): accept everybody where they are, provide an example, and let God work on their hearts about the things they know are wrong.
Fred Rogers reminds one of the Christian friends of whom C. S. Lewis spoke: they led their own lives in such a manner that he saw his own misbehavior as shameful by comparison.
Good examples, and oh so true. It is always helpful to look to Christ when trying to know how to handle matters of religion. He never lectured or condemned individuals, and in fact reserved His harshest language for the religious leaders of His time. He referred to them as vipers and compared them to graves that were white on the outside but full of filth inside.