In some people, the flashbacks can persist and cause significant distress or impairment in functioning, a condition known as hallucinogen-induced persisting perceptual disorder (HPPD)

I'm not sure why they conflated the two like that. The HPPD symptoms aren't what I would describe as a 'significant impairment in functioning' but I suppose that that's a matter of opinion. It's not the same as having flashbacks.

Hallucinogens can trigger or aggravate conditions like depression, mania and schizophrenia.

The only thing I can really say to that is to point out that by 'trigger' they might mean that it can bring out the condition in someone who is already pre-disposed. Everything I can find as a source says it will not make you have schizophrenia just by itself - or perhaps it might, but it hasn't been shown to so far.

Chronic use may cause persistent problems, depression, violent behavior, anxiety or a distorted perception of time.

I'd be interested in reading an explanation for this one. I'm leaning towards assuming that this claim relies on people having bad trips/traumatic experiences, and/or having the aforementioned pre-existing conditions. If not I'm curious as to what dosages over what time periods this happens with, if it's not explainable by those other things.

Either way, alcohol withdrawal symptoms still fit the bill. Even if LSD did cause schizophrenia/psychosis, the explanation that he has used LSD at any time at all in his past being the reason for his auditory hallucinations when it's known to occur with alcohol withdrawals is rather unnecessary. Correlation does not imply causation. Especially when it was an isolated incident - all his other hallucination experiences occurred with during the duration of the drug, except for the time he was experiencing alcohol withdrawal.