Take note in the future of who issue the first insult and who go off topic to do so as for example this thread the last time I look have zero to do with the proper ways to deal with your dying mother.
I'm in no position to judge. I'm a jerk, although I can't say I've ever made fun of someone for expressing grief.
But I do come from a culture that doesn't allow that kind of expression. When I was a kid, I sat with some relatives watching a TV broadcast about the new Vietnam Memorial in Washington DC. It showed a woman who found her brother's name on the wall and sank down to her knees weeping.
My great aunt became outraged at the display. She went on and on about how disgusting it was and then she said "Everybody's lost a brother in a war!" I was confused by her outburst until I remembered that her brother died in WW2. And I knew: she had never been allowed to openly grieve. Her anger at the sight of someone else publicly weeping was as close as I would ever get to knowing the pain she must have felt.
My experience is that grief for the loss of a loved one goes deep: to a place that isn't entirely rational. I can only imagine how Muslims suffering from sectarian violence feel. But I'm human. I know based on that, that they must become locked into the conflict. Eventually, the fact that Shias condemn the Companions of the Prophet in their ceremonies isn't the real reason for the conflict. It's that so many people have lost people they loved. To some extent, the violence we see is their grief.
If you've known grief, you know at least part of the story of the monsters you declare we must wipe from the face of the earth. They're your brothers and sisters.