Western Australians think the Eastern States stink and want to form their own country, so what?
That doesn't mean people can just decide to break up a country into lumps that fit their own ideals.
Actually, it kind of does, depending how you look at it.
What legitimises the power of the State over a given territory or population? What gives a State the right to exist?
If the people don't want it, they might take steps to change it. It's a matter of which side in the ensuing conflict is more powerful or, very often, which side has a stronger backing from an imperial power to help achieve an outcome. Naturally, separatist activity is rarely supported by everyone in the area (even the American revolution only had about one third active support), and it's usually considered illegal by the exisiting State authorities whose position is being challenged, and perhaps also under international law, but those factors have never stopped separatist movements and never will...
There are two main groups in this conflict, each backed by an imperial power, at least at a diplomatic level if not materially. Who will win?
Since the USSR breakup, when I was in Ukraine and other eastern block countries most have completely reversed many of the Russiaification programs by dropping Russian and Russian history from schools and even abandoning Cyrillic as the official written form of their local (but still Slovak based) language and switched to Latin alphabet. Ukrainian's all had to adopt Ukrainian names regardless of their names at birth. For example, Imagine being told your name is no longer Anna, but Hanna officially and legally and no chance to go back. This happened to a friend of mine.
Many governments have tried to undo what they saw as historical demographic distortions and create new ones (population exchanges, forced resettlement, cultural modification etc) but that doesn't mean they can enforce their policies forever if many people don't want it, nor that they have a right to do so in the face of public opposition. That's basically up to the people to decide, but if some of them don't believe the ballot box is their friend, they may choose other options.
I'm sure not all Russians were thrilled about moving (or being moved) to the Ukraine in the first place (just as the Greeks, Tartars etc who had been there for up to 2000 years would not have been happy about being moved out by Stalin), but the ethnic Russians have been there for a long time and maintained their cultural identity throughout. Tsarist Russia also sent Russian Jews to Ukraine in the 19th century to make them more Russian and less Jewish, and it worked, although most struggled as farmers. It's hard to imagine a new policy of cultural modification being well received by people in that situation.
And no more sanctions on Russia from Australia, eh? Our trade with them is probably only a couple of billion, but given all the strong words from our dear leaders...