It's only an "established slur" to some people (mostly in online niche communities), to a lot of people it's just everyday speech. Words such as retarded, special needs, intellectually disabled, moron, imbecile and more are all terms used to describe a disability, just like "blind". I'm tired of this artificially accelerated pejoration sped along by people who just want to correct others to feel good about themselves, the euphemism treadmill for people with intellectual disabilities in particular spins faster than for any other topic. We haven't invented 15 different phrases for blind in the last 50 years, there's no reason to do it for disabled brains any more than for disabled eyeballs.

Instead that energy should be focused on ensuring people don't use someone's disability to put the disabled person down. Those people are the real problem, not normal folks criticizing people for their shitty behaviors they can control, not immutable characteristics about themselves.