We really need to move beyond this taboo. If something that someone who is dead did in life was indeed bad, there should be nothing wrong with speaking it, even if such speech is derisive and caustic.
Think Hitler, Stalin, Mousilini, it would actually be a crime to speak well of them.
It only applies, like so many other things, to conservatives, and we MUST not speak ill of the LIBERAL dead. Horsefeathers! The world would have been much different if Adolf Hitler died in the trenches of WWI.
Stalin, Pol Pot, Mao Tse Tung, et al are all better dead than breathing.