Sometimes well-meaning people correct the language of people because they think it’s offensive, but end up doing something objectionable in the process because something is going on that they don’t understand.
For instance, people will often correct “autistic” to “people with autism”, because they’ve been taught that it’s more respectful, even when it’s an autistic person describing themself.
This also happens to people who prefer “queer” to describe their sexual orientation.
And lots of other groups.
So here’s some guidelines.
Pay more attention to what someone is saying than what words they choose to express it in. Words matter, but content matters more.
If in doubt, do not correct someone’s language.
Do not correct someone’s language when they are describing themself or a group they are part of, unless they are using a slur for a different group to be self-denigrating.
For instance, if someone who doesn’t have an intellectual disability describes themself as retarded because they feel stupid or unworthy that day, it’s ok to say that’s offensive and bad.
If someone who *does* have an intellectual disability describes themself as retarded rather than some other word you’ve been taught is more appropriate, do not correct them and tell them to use a different word. That’s their business and not yours. And aggressively paying attention to language rather than content is not respectful of the person you are talking to or the group they are part of.
If you do that, it means that you’re saying you’re only willing to listen to members of a marginalized group if they use language you approve of. That’s the opposite of respect.
And generally speaking, do not insist that someone use precisely correct language as a precondition for listening to them. Words matter, but content matters more than words. Respect matters more than words. They are not the same thing. Someone can use all the right words and still say horribly dehumanizing and awful; someone can use bad words in respectful and humanizing ways. Make it about content first.