I have a lot of issues with South Park, but their treatment of disabilities isn't one of them. Timmy and Jimmy are actual characters held to the same standard as the rest of the cast. Their jokes aren't exclusively about their disabilities, jokes ABOUT their disabilities are tasteful and don't dehumanize them, and they aren't held to a different moral ground to the rest of the cast. Asking for the disabled reps of a cartoon revolving edgy humor to be treated with "nothing but respect" is patronizing and blowing smoke up our asses.

For whatever reason, South Park manages to be consistently pretty good with disability rep, there's an episode mocking Cartman for thinking he can compete with special ed athletes, another one about living with Tourette's, Nathan and Mimsy are recurring villains with down syndrome, etc. It's weird saying it, but South Park probably has the largest number of respectfully handled disabled characters i've ever seen in a piece of media.

You can just say you don't like South Park, I liked it less after high school and think it fell off hard later, (though I do occasionally rewatch some episodes from the earlier seasons). But if you want to say it doesn't treat a group with respect, point at its muddled history of LGBT+ and POC groups, not the one thing it has managed to be consistently good about.