Gallows humor is very hard to pull off without being involved yourself and there is the clear danger of overdoing it. I think the replies are an example of both.
You, my friend, lack a sense of humor.
You'd expect a comment like "I'm caught up with some day job work at the moment" to show up, but this one is clearly pulling humor into the situation, so I think the responses are relatively in matching humor.
People are complicated. I have been to funerals where it is almost like a roast. Some people deal with heavy emotions through humor.
I do understand how if something doesn't affect you it can be very disrespectful to mock it. I am just pointing out that not everyone holds a reverence for even very serious situations.
But the comments themselves are tired and not funny. They seem more like shills for karma or whatever is of value in their community.
I recommend looking up the evolutionary purpose of laughing. Then apply it to the people who used humour in this instance. IMHO, its a perfectly natural response. Appropriateness is there for irrelevant. Certainly not an issue by which one should get one one's high horse and judge others by.
As such, I have to ask: Is it appropriate to judge such people?