Idk I don't want to be too harsh on LW - most people are just fucking bad at helping their loved ones through times of grief, even if they've lost loved ones themselves. And that's not accounting for the particular situation of losing a dozen people in a few weeks. LW knows they don't know what to say; they said they thing they thought they were supposed to and realized they've angered & hurt their friend; they also don't want to just leave their friend alone to suffer. Like, they're literally asking for advice on better things to say. It's better than what like 90% of people do in that situation, which is just ghost because they're too uncomfortable.

That said, the response is pretty awful. The LW needs advice and insight into the mind of someone experiencing that kind of complicated grief, not vague things about being uplifting. When that's the advice they get, how can you be surprised they have no idea how to help their friend?