Well he can't defend that rude comment..can he? Because he was murdered....by someone that hated him as much as you. There is nothing constructive in what you are saying. A complete void...and sad. Good luck out there.
Let's see, then. How should we speak of Hitler? Imagine he'd just died. What about Fidel Castro? He died much more recently. Would it be "unfair" of us to point out his faults? Criticize his politics?
What does not make sense is imagining one should never speak ill of the dead. That is inappropriate if they've pushed reprehensible ideas, or hurt others.