Macabre? No more macabre than any other posthumous award I would have thought.
There's a difference between giving a person an award posthumously, and making up an award for that person, posthumously.
If Morrus wants to establish a "lifetime achievement award" for the Ennies, then by all means, Gary Gygax should probably be the first to receive it. But that's a bit different from taking the electronic equivalent of a Bedazzler to his forum account.
Imho, anyway.