If we are going by his Tapatalk posts, he does have it. He saw ophthalmologists, psychiatrists, had imaging done of blood vessels in/around his eyes, was tested for migraines, etc. At the time he was posting about this (2009-2012), it was really hard to get a diagnosis of VSS. It's not something most GPs or ophthalmologists were well versed in, and many still aren't. My 22 yo son was diagnosed with it in 2019--and that was only after going to the psychiatrist, GP, ophthalmologist, neurologist, having a MRI, tons of blood work, and finally getting a referral to a neuro-ophthalmologist at a major teaching hospital where she did a ton of tests. There really are no tests to confirm VSS--it's more a matter of testing to eliminate other possibilities...which is why it's often not diagnosed. The medications he mentions and the effects they had are all in line with VSS. The mental health effects he mentions such as disassociation/depersonalization/derealization can be quite common with VSS. Personally, I don't doubt that he has it. It's certainly not an excuse for his behavior, but given how for some people VSS has some very strong ties to mental health issues (if the VSS wasn't caused by LSD or marijuana use), it can help give us a better picture of aspects of his personality.
And before someone brings it up again--VSS does not make night driving impossible for everyone. Because VSS has different causes and triggers, for some people their vision is better at night. Lower light for my son both reduces the intensity of his VSS and makes it easier to "ignore/adapt to" the lowered VSS. For him, broad daylight makes it much much worse. For some VSS patients, the absence of bright lights does not reduce their VSS, so their VSS is just as strong at night time as it is during the day.