Personally, I think autistic people should be allowed to donate sperm or eggs, but that the intended parents (the ones raising the child conceived by donation) deserve to know what their kids are likely to be like, and make an informed choice. Otherwise, the children ultimately suffer from being born to parents who are hung up on wanting a different kind of child than what they got, just like many autistic kids born to NT biological parents experience.
Unfortunately, due to the negative perception of neurodiversity, openly autistic people are barred from donation through official fertility clinics for eugenic reasons. This is despite the fact that there are some people who would rather have a child on the spectrum, just like there are parents who want a deaf child.
What I'm uncertain about is whether it's really important to disclose the diagnosis per say. A lot of sperm and egg banks give detailed personality descriptions of their donors to the intended parents, including things like what their hobbies are, how athletic they are, how well they did in school, etc. If an autistic person didn't give their diagnosis but described their personality honestly, there'd be a lot of hints about autism in that. A knowledgeable person can look at a description like that and say 'this person has a high probability of being autistic' - just as many people do on this forum with descriptions at a similar level of detail. Most intended parents won't know those are signs of autism, but even so, if they're expecting a quirky, socially awkward, clumsy kid with strong interests in unusual topics, a high functioning autistic kid wouldn't be that much trouble for them, would they?
After all, I'm sure there are plenty of undiagnosed autistic people who have donated sperm or eggs. Donor X, for example, sounds like he may have been an autistic guy.