I see no sense in this.
Death is never a good thing even if Leo had offended you indirectly in the past you should at least bid him a farewell based on his condition. Not everyone is strong enough to fight cancer for over a decade.
Besides that you have no proof to what you are saying. And for the record Leo was so much help to me during my newbie journey especially when it came to protecting my coins.
Behaving like this on the forum shows you would do worse in reality.
Actually, I would say the opposite. Since o_e_l_e_o doesn't have much time left to make things right, he should use this chance to correct the record and apologize for knowingly spreading lies about weaknesses in Bitcoin's privacy. Bitcointalk posts are a legacy you leave behind even after you die, so it's worth it to make things right.