The problem is that you are saying Asperger's causes impulsive business decisions. Nothing in your quote supports that contention, and it's a terribly ableist thing to say.
In fact your quote suggests the opposite-- people with Asperger's tend to be bound to routine rather than impulsive.
I think the parent comment is just especially touchy to these comments.
It wouldn't be wrong if you replaced Asperger's with say ADHD.
Be careful of slapping -ism/-ist labels on anything that offends you personally when there's no clear discriminatory intent.
Discriminatory intent isn't required, a discriminatory outcome is. Random people with ADHD don't need to catch strays here.
The criticism is that he is impulsive and that he isn't properly managing himself. No diagnosis is required.
You can clearly tell that Musk has Asperger's just from hearing him speak or even reading some of his tweets (at least I can, maybe because I have it too), is making that observation also "ableist" or do you only consider it to be ableist because it is attributing his managerial decisions to that?
We may be arguing semantics because nowadays "-ism"s are used as shorthand for generalization instead of prejudice and I prefer to stick to the latter definition to avoid attributing discriminatory intent.
No, you can't. Not even a certified medical professional would claim to be able to "clearly" diagnose a patient based on their public persona.