I don’t think it’s rude to ask the cause of someone’s death
I’m sorry but why exactly is this considered a rude question? Numerous times I’ve seen a famous/known person pass away and any time someone shows some type of curiosity about why or how someone passed away they’re shut down quickly as being insensitive.
It’s especially strange when someone young/healthy suddenly passes away and you’re expected to just send condolences and not ask any questions.
Now I wouldn’t hound on close relatives or friends if they weren’t comfortable talking about it, but as a concept this person has just left this planet forever, I think it’s reasonable to want to know what caused it without that making you a conniving nosey gossip etc. #conversation