I have no wish to see the pilot un-necessarily denigrated or picked over in public, but I have to say that there is absolutely no evidence of cognitive impairment or incapacity to be a contributory factor in this accident.
This is almost getting silly to be honest. Just because an experienced pilot appears to have made a catalogue of uncharacteristic errors during a flying display, which you maybe wouldn't expect, then everyone rushes to say that he was impaired or incapacitated.
Maybe he had a bad day? Maybe he was complacent? Maybe he was ill prepared? Maybe he made a series of errors of judgement?
Could that not be it?