[GreenWinters]

> Using в quickly became standard in Ukraine, and the choice of в versus на became a sort of liguistic tell to a Russian-speaker's political and cultural tendencies.

Doesn't seem THAT telling to me. Saying "на Україні" is very common in the Ukrainian language, and lots of Ukrainians use bits of Ukrainian while speaking Russian. I wouldn't be shocked to hear "на Украине" from a Ukrainian, and I most definitely wouldn't make assumptions about political tendencies based on it.