Is it normal my dad got violently angry over this

My grandmother died recently and my mom who's been taking care of her for years was trying to arrange the funeral. But since grandma borrowed against her life insurance policy there wasn't enough to pay for it, and she's exhausted her own funds taking care of her so she asked my dad for help(they're divorced)

My dad has lent my mother plenty of money and he certainly wasn't going to to turn her down this time, he gave her the funds no problem, though I'm sure like anyone he's annoyed to be out 4 grand the money itself isn't what he's mad about.

He's angry that mom has two brothers who haven't even attempted to help pay for the funeral, and one of them we know for sure has the money to help, since he paid for everyone who attended the funeral to eat at chilies and several other things that day.

It's a principle thing he thinks it's sick that they aren't trying to pay for their own mothers funeral. He got so mad he said when they sell grandma's house he's going to get his money back from my uncles or he's going to beat the shit out of them. He was so angry I asked if he'd been drinking because normally he only gets that riled up after a few beers, he hadn't he's just that pissed IIN?