Where are the writings in the game that actually indicate the structurally intact comet ruptured? This sounds entirely like theory, so counter theory is that exactly 2 min after a comet full of ghost matter collides with the sun all life in the solar system gets wiped out, and that is the rupture they were concerned about.
I understand the theory that ghost matter cannot penetrate water is substantiated by gameplay, but deriving story from gameplay is bad, you don't know what is oversight, a bug, or something the programmers didn't think about. Given the Heathians developed infinite rocket fuel and the Nomai need stationary gravity canons to travel it's quite easy to argue (though the story writers clearly don't want you to think this) that Heathian space technology is superior to Nomai. Heathians also seem resistant to immense heat as you can stand in a volcano on Hollow's Lantern without issue. Heathians also have critical organs on their skin since touching a cactus can kill a heathian. Heathians don't require water to live (and it's quite debatable how Feldspar gets his marshmallows). Heathian trees require no nutrients to grow and produce oxygen even where there is no atmosphere.
--22.214.171.124 04:04, 22 November 2020
The issue wasn't that the comet ruptured, it was that the spherical stone casing inside the comet ruptured, which contained the Ghost Matter:
- POKE: The spherical stone casing here seems to be the source of the energy readings... No, rather, the source is what’s within the stone. I’m detecting some form of exotic matter.
- PYE: The stone is muting our energy readings; they should be ten times what we’re seeing, at least.
- POKE: Pye, I don’t think we want this matter interacting with us. As far as I can tell, direct contact with it would almost certainly be fatal.
- PYE: I’ve never encountered anything like this casing, but it’s all that’s protecting us from what’s inside. Worse still, this matter is disturbingly volatile.
- POKE: ...Pye. Whatever the matter inside this stone casing is, it’s more than just profoundly unstable; it’s under tonnes of pressure. Look at this density scan. I’ve never seen anything this tightly compacted before! What is this?
- PYE: This is orders of magnitude worse than I’d imagined. If this stone were to rupture, the lethal matter within would rapidly expand, completely blanketing this star system almost instantaneously. And the pressure is still building as the comet approaches this star system…
Ghost Matter being negated by water was confirmed in an interview with one of the lead writers, so that's not just a gameplay thing.