You can't make any word a slur. Slurs are specifically words used to show prejudice or to oppress a group of marginalized people. You're not going to use the n-word, are you? So don't use words that historically and still is used against intellectually disabled and developmentally disabled people.

Your "deal with it" rhetoric also doesn't come across as anything else but a lack of good argument. You know you could just be a nice human and have empathy for people who are hurt by the words you're using instead of being a stubborn asshole.

In my country the phrase "jævla homo" is a slur against gay people. So just because a word has multiple meanings doesn't mean it isn't a slur when used in the right context.

And please spare me from your passive-aggressive winking faces. It doesn't come across as anything else but childish.

Yes it is. For example if you read the article I've linked, you'll notice it does include the adjective.

But even if anyone is offended, that doesn't make them wrong. Being unharmed by slurs implies privilege, not rationality.