"Neurotypical"
Definition from oxford languages supplying google definitions: not displaying or characterized by
autistic or other neurologically
atypical patterns of thought or behavior.
The first use of this in the definition is "not autistic". The second definition is "not atypical in some other fashion". I've only ever seen this term used to mean "not autistic", as the other definition renders the term almost useless and quite difficult to apply. It requires understanding that the person or people, or thought process that you're characterizing somehow as neurotypical is/are in fact not atypical in every other sense, and that is a large hurdle. I've never really seen someone try and would be surprised to see someone attempt that outside of a clinical setting.
I know someone with a personality disorder. It's undiagnosed, because this particular disorder prevents the afflicted person from seeking, accepting, or otherwise submitting to any form of psychological diagnosis. So far, attempts by clinicians to evaluate this person have resulted in the clinician being immediately fired by the patient. Regardless, myself and a large group of others have all reached the conclusion, with a lifetime of evidence, that the person does indeed suffer from this disorder.
Referring to this person as neurotypical because they are not autistic is absurd. Referring to them as neurotypical because they lack a diagnosis is equally absurd. They are extremely atypical, and their condition appears to be less prevalent in the population than autism at least based on my own anecdotal sampling. It is not a safe assumption, nor is it respectful or appropriate to assume that because someone is not autistic that they are "typical". Defining everyone outside a particular condition (autism in this case) as being "typical" is reductive and lacks empathy and consideration that there are other conditions and afflictions that affect people's lives.
To compound the problem, suppose that people with a certain personality disorder adopt the same term, "neurotypical". Now autistic people are neurotypical in the respect that they do not have this personality disorder. Suppose people with yet another personality disorder adopt the same term. Now autistic people and people with the first personality disorder are each "neurotypical". It's inappropriate for people with each of these sets of thought patterns to refer to people with different thought patterns as "typical". I'm not sure what a typical thought pattern looks like, and I'm not sure it exists.
So how about we use "not autistic" instead of neurotypical? The answer is because, at least in my experience, reducing everyone who is not autistic to "typical" appears to give autistic individuals some level of comfort or even pride. "Typical" can be used as a pejorative, and can even give people a sense of superiority, perhaps even just in certain respects. I suspect that this is why this particular meme is self-replicating within the autism community. To the extent that this offers aid to autistic people, it does not come without a price. It is a barrier in many respects to interacting with and getting consideration from people who are not autistic.
"Not autistic" should apparently suffice.