yes and also no... (sorry for such a confusing answer but. allow me to ramble anon)

no as in like, there is no Reason as to why i write nik autistic.. he just Is. that's who he is! i think he does have autistic traits and as an autistic person, I Know What You Are. i just tend to write nik a certain way and often times that certain way is just Autistic and it's like, well fuck it! also i do think he and keng are autistic4autistic so its like awwww 🩷 let's all be joyful

as for the yes side of it, i think it does add to fics sometimes! for my most recent one, it adds A Lot. unfortunately it does make keng somewhat ableist in a way but Lmfao. nik can't do anything!! he's treated like a baby!! the way he's treated is rooted in ableism so it does add more if he's actually autistic because it's not uncommon to be treated that way! i think slipping in disabilities is very fun (not as in having them. Hi please don't cancel me again) but i think using them as a way to understand how things have gotten So bad (in ref to my recent kengnik) is like Wow!! okay!
anyway anon it's very fun to write nik as autistic and i think everyone should write him as such bc. it's not hard to write him as so because well. Look at him. also i'll write autistic4autistic kengnik at some point just give me a moment. GIVE ME SOME TIME.