1. Why would you need to?
2. Autism ≠ Retarded

Only in the proper context. For instance, it’s perfectly fine to say, “The foam retarded the fire as designed and saved many lives.”

If you’re meaning the former disability-related meaning that is now widely considered offensive when applied to a person, why would you possibly want to? There are more appropriate words to use.

Just as okay as for everyone else.

If by r-word you mean resplendent than have at it! Thank you for rage baiting with us today.

Is there some reason you feel a need to use it?