He can certainly rub people the wrong way. He likes to share his opinion on stuff, in a ott manner. You don’t have to agree with him, and I’m pretty sure he will listen to your opinion (without agreeing). I think he likes a world where people have opinions and share them, and he often did it with wit, so don’t take everything too literally.
Many others in “the business” would’ve either ignored the mail, or demanded some form of payment/contract/licence agreement.
He took the time to respond, and gave him the go-ahead to do whatever he wants. Can’t think of anything more generous than that (sharing his time, and his creative output).
He helped a lot of up and coming artists by making his services affordable. Across all genres. One of his tenets was that if an artist did something in the studio that he didn’t ‘get’ and would consider a mistake for his own music, his first instinct should be to trust that artist and let them express themselves. Something many, many other top producers/engineers could’ve learnt from.
If you approach it as “actions speak louder than words”, he might be more palatable. And definitely you have to keep a sense of humour when listening to or reading some of his words. He often spoke hard truths, sprinkled with lots of humour.