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.
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 extend eternity your honesty.
No matter how things are between you and o_e_l_e_o I don't think him having a short time to live is something you should be happy about, is like you're taking advantage of the fact that he's not going to be here to defend himself to say some crazy things.
Come on OP, even if he did something you don't like or he stole your money or something, that shouldn't make you wish him death, at least he never prayed you stop breathing , give him the last respect he deserves and not the way you're going about business. Try and keep a better legacy too, who knows this guy o_e_l_e_o can make it past this month next year and many more years, I just wish him well where ever he is.