I dunno, the thin man looked pretty pissed at being in the interrogationmabob.
Being locked into a glass container and being shocked with energy/magic would make me angry too.
I prefer interrogationmabob.
I didn't say they liked Humans, plus the interrogationmabob kills everything that gets put into it. I get the impression it's a final "I'll die but I'll screw you doing it" bid to give Humanity some information that we could use to fuck over the Ethereals.
I don't know, the mutons -> heavy floaters seem even more extreme than the thin men.
The mutons are some of the least modified, from where I'm standing. They even still have some of their culture, what with the tattoos and warrior race attitude.
The floaters are mentioned in interrogation as being almost mindless balls of rage. They don't have complex enough thought to hate the Ethereals, or at least not more than they hate everything else. The Thin Men retain their cognitive skills and can comprehend what was done to them.
And the Ethereals mention the thin men as their most loyal units.
The Thin Men were designed for deception, so perhaps the Ethereals got more than they bargained for.
I just expect the thin men have low willpower and a natural tendency to follow orders - the same traits that make them so useful to the ethereals are the traits that make interrogation rather easy.
While game mechanics are not exactly evidence, in my experience Thin Men have high Will, since its so hard to make them panic.