I can see both sides of it.
As far as the brother goes, it's important to keep in mind that all of this may be a response to his childhood trauma. Our brains selectively recall good memories and forget bad ones as a protective measure. Keep in mind that no abusive person is abusive 24/7. Abuse goes in cycles. It's quite possible the brother has blocked out the abusive occurrences, and also quite possible he didn't bear the brunt of the abuse. In order for him to admit that his father wasn't a good dad, he has to admit that during his entire childhood, his needs for basic security and safety were not met - and those are second only to the need for food, water, and shelter in the hierarchy. He may not be at a point where he's ready to admit that. As an example, GFIL was awful. I haven't met him but I've heard details of what he did from Hubby. He was emotionally and physically abusive to his children, and did worse to his daughter. He was emotionally abusive to his wife. His GC were scared to death of him. But FIL (who was the favourite son) sometimes talks about St. GFIL of Blessed Memory and says he didn't see the negative side of him.
Then, too, there is the fact that however remote the possibility, there remains a chance for reconciliation as long as the person is alive. Death destroys that possibility. OP's brother may be mourning that as much as he is mourning what was.
Bottom line: while I think what the brother did was in questionable taste at best, I don't think it was appropriate for OP to let him have it.
Shall we reboot our cartoons thread again? 😁
Is there such a thing as delicious ready meals?