This is a poor argument. Sure, there might be some harm from their death, but you’re tacitly assuming that said harm is greater than the harm they are currently enacting. And you’re assuming something we have tons of evidence will not happen—that they would recover and start taking the illness seriously.
A good moral argument must weigh both sides. And it may wind up that something that was ordinarily a bad thing, like wanting someone to die, is not so horrible. As I’ve said before, I don’t remember anyone saying they’d rather Osama Bin Laden have become a US ally than for him to be killed. So clearly there is a line for most of us.
That said, what I mainly object to is people expressing anger like this, and then some people have to come in and say why their anger is wrong. It would be one thing if their anger wasn’t justified, but it it very much is. I don’t see what these posts tut-tutting people for their anger actually accomplishes. You didn’t even try to frame it as your own personal reaction.
Plus not every expression of how we feel is going to be moral. The OP didn’t actually say he wants them to die. He said he does not hope for their recovery. I think that’s more honest than the platitudes. A lot of us would be happy if someone as bad as, say, Abbot were to die off. It’s hard to argue that his existence has made the world a better place.
It may be “wrong,” but feelings don’t distinguish. All feelings are valid, including the anger that happens because of grief. And this particular anger from grief is a lot better justified.
That’s what this is: we’re grieving the deaths and angry at those who are actively causing them.