I love how you point out that the characters are all believable, flawed people. I love Avasarala's character (and the actress' voice on top of that is like icing on a cake), and the way she plays the Power game so well. I really dislike that her character would torture, but at the same time she's like a well-written villain. She doesn't quite fit on an alignment chart.
> ALL of them stole their ship from the people of Mars
I'm not sure how it is in the book, but in the TV show, a ranking officer of the Martian navy explicitly tells the ship that they are in control. As legitimate salvage goes, it seems pretty defensible. The only reason they don't go deeper into it seems, to me, to be because explaining that (and proving it) would be Very Hard, and they'd rather avoid the risk.
> a ranking officer of the Martian navy explicitly tells the ship that they are in control.
Yes, that's how they got possession of it and managed to make use of it. It is not at all the same thing as relinquishing ownership, which that Martian officer would not be able to do in any case because he didn't own the ship. The reasonable expectation is that they use the ship to do the job they needed it for, and then return it to it's proper owners.
This is, of course, only the second worst case of piracy thinly disguised as salvage in the Expanse. The title for the worst case of course goes for Behemoth.
> ALL of them stole their ship from the people of Mars
I'm not sure how it is in the book, but in the TV show, a ranking officer of the Martian navy explicitly tells the ship that they are in control. As legitimate salvage goes, it seems pretty defensible. The only reason they don't go deeper into it seems, to me, to be because explaining that (and proving it) would be Very Hard, and they'd rather avoid the risk.