You know, this argument is pretty deep.

Sollux is angry that, while they are offshoot, the other ghosts are still their friends. Still have feelings. And Vriska is ignoring them and letting them die without so much of a second thought.

While Vriska, she can’t meet them all individually. She doesn’t have dead-powers like Aradia. She doesn’t have time with English destroying everything. And can you really take the idea of thousands of your friends dying? The better way to not have That^ take a toll on your heart is to think that they aren’t really her friends, which is what she decided, and instead focused on protecting her specific friends on the crew.

Basically, this is a very hard issue to tackle here.