As I already said, I do not deny that these region has a shared history – that's a common fact . I was mainly objecting to the article calling Ukrainians "invaders".
With that, I would agree with you 100%. It's wrong.
The site's ridiculously short piece on the etymology of "Ukraine" is even worse. But then again, it is by noticing that we can correct. Seeing Polish-Ukrainian shared history, it actually baffles me and to why so many sources are either solely Polish or Ukrainian. At least, the ones that I have seen are. Surely, there must be some academics From Kiev, Kraków, Lviv and Warsaw who see the great benefit of having jointly researched sources.