Where to draw the line for Habeas Corpus

There's a lot of controversy over the recent supreme court split decision re habeas corpus.

The constitution says "The privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it." That's clear enough.

But it seems to me that the central issue is this: was it really the founders' intent to have habeas corpus apply to the invaders themselves, or just to those being defended?

What about invaders who are sworn to the destruction of all we stand for? Perhaps habeas corpus is a privilege of status as a US citizen, resident or authorized visitor.

Are soldiers going to have to take judges onto the world's battlefields in order to decide who can be detained? Is it OK to kill enemy soldiers in time of war, but not to detain them?

What if we're invaded by space aliens? Does habeas corpus apply to Martians? What about microbes? Shouldn't a microbe have its day in court before being quarantined?