Posting pictures and updates can be more efficient and less traumatic for the family than making phone calls. I’d err on the side of sympathy for the family.
That being said, I’ve had enough of those who post pictures of kids they don’t even know, be they dying of cancer or having Downs or whatever. There are just click baits of people trying to make money on their Facebook page and often don’t have the permission of the parents of the child in question. Just as bad are the "Facebook will donate $x for every share or like. No, they won’t. Nearly as offensive are the “like=10 prayers, share = 100 prayers” bullshit. That’s not how it works, ask your religious leader.