How can they be a judge of its quality or flavour?
(He did say in a previous video that he wont eat any hot curries.)
I feel like i'm defending Adey but I am not , just adding my two pennies so to speak. Surely the quality and flavour is judged by his customer, if the return and order again , then surely that is his measure.
There was also a vegetarian chef on Great British Menu that cooked beef, I can't recall how he did but that doesn't mean to say he can't be trained to cook food he will not taste. He did have others around him to taste the dish for him.