Not entirely sold on the idea. In fact, I think it's more likely Anisa is the narcissist. My take on Ian is that while he projected bravado and confidence during his Cancer Crew days, he was an unironic incel and a very insecure, nerdy guy with a lot of issues that he hid behind clever editing.
Even back then, he exhibited a lot of plainly awkward and unironically autistic behavior, such as lashing out at HowToBasic for throwing eggs in a skit and a weird obsession with Maxmoefoe. I do think he might have some kind of mental issue. However, I also think he might just be a plain bad person. Sometimes people are just evil. There's no need to attribute it to a mental illness.