Earlier quoted context omitted.
In Athens, an "idiotes" was a citizen who focused only on private matters rather than participating in the polis (city-state). Because civic participation was considered a duty, this term carried a negative connotation of being socially irresponsible or uninvolved. This term evolved into the modern "idiot" which we are familiar with.
Well wasnt that a good thing? After the extermination of Melos they could credibly say they were less responsible for the actions of the polis. And had a higher chance of deflecting the inevitable revenge on to the non idiotes Athenians.
For one thing, wouldn’t everyone claim they were against their old polis? How would the invaders have any idea who was an idiote?
I just don’t believe it’s at all easy to avoid the fate of your nation , and I especially doubt that the politically ignorant have a better chance of avoiding that fate than the well informed.