I would rather go find my effort post on the topic, but simply put, I see no issue with people having joy in response to someone's death, I personally don't, for very specific personal reasons, but beyond any contempt an individual will have towards someone of note, it could also be a net positive for showing the remaining population would could lead to celebration following your death.
The arguments I can see for being against celebration, I just see more pitfalls for those than the current position I hold to, like imagine a world where Hitler's death would be wrong to be celebrated, Saddam Hussein, Idi Amin, Pol Pot, etc. Why shouldn't their deaths be celebrated, well I can see an argument from the determinist point of view but 99% of people don't near anywhere towards holding those kinds of takes, so really, the only argument I can think of, is not wanting to cause the related family members harm, but, it still stands that family or not, a wrong is a wrong, and if a family member can't see that, it's understandable, to an extent, but still doesn't negate the harm done. I suppose we can argue about the approach of celebrating, I just don't seen anything of note there, or we can argue of the impact it can have on the population, but I don't see that playing out well for the "against celebration" side.
I mean, if you have the argument, present it, I'm all ears, needs to be beyond some moral "respectability" nonsense though. I have been dealing with this argument for a while and it comes up every time someone of note dies and a notable celebration follows. I come across comments saying we shouldn't celebrate and it's wrong to do so, but they have no arguments to support it, it's just a "I feel this is wrong" and then I get into typing some long ass response about why it really isn't "bad" to someone that didn't think the topic was all that important, but of course felt the need to make a declarative on the topic.