As a neurodivergent woman myself, with two neurodivergent DC, I thought exactly the same. OP and both her boys sound ND.
OP, when someone asked if he could be ND, you answered that he goes out to work. Lots of autistic people work, have friends, families, social lives etc. It really does depend on the level of functioning and ability to mask.
You say he’s not mocking you on the phone calls. Nor does it sound as if he’s mocking his younger brother during meltdowns. He sounds clueless and unaware rather than spiteful.
The situation re date night and being told to stay away also screams neurodivergence to me. Theres something called RSD which is common with ND folk. It’s extreme sensitivity to being rejected/feeling rejected. He sounds as if he has no idea why it would be inappropriate to keep barging into a romantic meal and felt pushed out in his own home. That’s not a normal reaction and really does suggest neurodivergence.
Also worth noting that lots of ND can appear controlling - it’s a way of coping, reducing the unpredictability of the world which is really hard for many ND folk. I’m not suggesting it should be just accepted or ignored, but there’s not a malicious motive behind this type of behaviour.
I understand that you’re scared of losing him if you tell him to move out. If you think he’s capable, and you think it’s in yours and his best interests, it’s something you could work towards. However it would be helpful to structure it as something positive for him, rather than “you’re in my space and we don’t want you here.” You could maybe agree that he comes home on X days so you both know where you stand. However, I have to ask whether he has the skills to move out and live independently? I really do think you need to be brutally honest with yourself here.
I know you should be able to just say to your child “don’t you think it’s time you found your own place?” - but my comments here are on the basis of him being ND. He really, really does sound it.