Not how it works with ethnicity or group identity.
Like I said. you can argue that "Ukrainian" identity should not qualify as a ethnicity. That's fine. But to say that "Ukrainian" doesn't exist, it's only a lie and made up word, that is simply wrong. Because it does exist as a group identity.
The Qin unified China, and assimilated Chu culture back into 中原 （Central Chinese Plain), but this does NOT mean that Chu identity never existed. It still exists to this date, it's just not a national/ethnic identity. And if China was never unified like how Qin did, it is very possible that Chu will evolve into a major ethnicity or even be the mother of several modern day ethnicities. But that's in a alternative timeline.
This is the same with many other cases in the world. For a group identity, once it comes into existence, then it exists. Even if it ceased to exist, it still has existed once. You can argue that its nature does NOT really qualify what it claims, but there is no denying its existence.
Ukraine has at east existed as a country since 1991. You can question its nature, its legitimacy, its stability and integrity. But you can't just downright say that "there is no such thing as Ukraine", "doesn't exist", "all a made up lie".
I am not a simple anti-Russian person who just bash for the sake of bashing. Not at all! I insist on this because this is both bad for Ukraine and bad for Russia. This make Russians look like absolutely incoherent brutal barbarians, while in reality, Russians could have meant to say something much more complicated and much less blunt.