I think making a point broadcasting that one doesn’t care if other people who weren’t harming anyone die is callous, yes. Doubly so when one does it on a news story about people dying.
TBH daily, about 150 000 humans die, and I don't have the capacity to mourn them all.
That said, as you say, broadcasting that one does not care without even being asked is already an attitude and I wouldn't like to be in any sort of relationship with a person which spontaneously emits such messages.
Hmm. I don't know. I am glad they're not harming anyone else, but also -- like, I have kids. And if they were to get into this sort of thing, I'd at the least be like "Well, that's STUPID. Why put yourselves in harm's way deliberately like this. Stressing me and mom out. Do something that helps someone else instead."
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The thing is, they can and do harm others. Not just family and friends when they perish, but rescue workers who risk their own lives to save people who get into trouble. The article talks of 2 people who delivered her supplies, one died, the other has gone to Germany for frostbite treatment - as fellow climbers maybe they don't count in quite the same way, but rescue workers do die or get injured as well.