Who wrote this?
This is definitely not an autocorrect mistake. There’s no way that you can get from arthritis to the cute little cartoon character that is Arthur without some kind of misunderstanding. I do think that more people need to download some kind of spelling and grammar check software before they post on Twitter.
I do love Arthur, though, and I’m sure that he would have had some cute little parable about how learning to listen and spell is very important for making a good impression in life. Then again, this person probably wouldn’t listen.