While I do think this situation is tragic all around, I feel the need to post the definition of “Joke” from Wikipedia:

“A joke is a display of humour in which words are used within a specific and well-defined narrative structure to make people laugh and is usually not meant to be interpreted literally. It usually takes the form of a story, often with dialogue, and ends in a punch line, whereby the humorous element of the story is revealed; this can be done using a pun or other type of word play, irony or sarcasm, logical incompatibility, hyperbole, or other means.”

And so I think his comment was an absolutely valid joke. You can joke about horrible things and still remain respectful. Actually it’s a very therapeutic and didactic thing to do, if done right.