Hitler’s family was “grieving” too no doubt. Mr. Phelps was astray, led his family’s flock astray (they made up his church/cult since 1955) and his efforts demonized Christians in the view of the popular media (perhaps deliberately so as homosexualists now acknowledge he did wonders to turn those critical of homosexuality into “G*d hates fags” boogeymen).
I can be critical of Phelps’ church just as I’d hope that so-called moderate muslims would be critical of Islamonazi terrorists. There is no rational defense of Fred Phelps and criticizing him actually defends the faith of other Christians (from foul interlopers trafficking in the name of Jesus). I’m not a defender of the televangelists either (often religion’s “professional wrestlers”).
And we can do that without celebrating the man's death.