Ironically, after WW1 Polish ethnologists undertook research which showed these groups spoke a dialect of Polish, and so were Polish. After WW2, with Akcja Wisła, they had suddenly started speaking a dialect of Ukrainian!
No sane scientist could say they were speaking Polish dialect. What the ethnologist tried to do was to diminish that very fact and expose other cultural aspects as more important. And some aspects were indeed of Polish or Slovakian origin as the substratum and adstratum of £emko culture.
But there were also some nationalist politicians who wanted to protect £emkos from Ukrainian nationalist propaganda. However what they say, I think, isn't so important scientifically.
2 facts you put together don't fit together. The pretext for expulsion of £emkos was that they give shelter and support to UPA rebels, what wasn't generally true.
It was sad and unjust for £emkos.