I don't watch Arthur because I'm not ten years old. How were we supposed to know?
If it was just the character grooming himself a lot or talking funny, rather than being seen around town with other men under his arm, I'm going to bitch about it. This comes off as conditioning in the literal definition of the word, teaching kids that if someone has certain innocuous traits then they have to be a certain way. Like, what are you doing to the little boy who identifies with something Ratburn does in the show? Are you encouraging him to be gay? Are you teaching his peers to see him as gay, or accuse him of it?
From an outside perspective this comes off as distasteful stereotyping, yet it's being painted as a good thing. It's approved of by the cult of equality and PBS programming is literally funded and produced by the federal government, so nobody's allowed to question whether or not this was a good idea. Never mind the fact that, even if everything I've just assumed is all wrong, it's still just a bunch of people in show business jerking themselves off over how progressive they are.