Really lame western propaganda. The regions in contention were part of Russia and as to be expected many Russians lived there. In particular that region was part of the Don Cossack region of Russia. Now a large chunk of the Ukraine is substantively Zaporozhian Cossacks and the conflict is really between those two groups. Now as you can or at least should be able to imagine those Russians living in the area that used to be part of Russia have many, many relatives in the rest of Don Cossack Russia and oh yeah some are in the Russian army or were in the Russian army. To think they would not volunteer and cross the border when their relatives are being killed is so damned stupid. To think the Russian government would seek to make itself look really bad by trying to stop them, is even more stupid.
I have seen a photo a self declared military volunteer from Abkhazia of all places, not there because he is defending Russian but to be kill puppets of the US (for the obvious George McCain reason, had to shoot his mouth off with "I am Georgian"). Volunteers are coming from all over Russia to fight the US and the Russian government has zero intention of suffering major political damage by trying to stop them. The Don Cossacks would be furious if the Russian government tried to stop them.
So the whole escapade was a fucked idea from the get go, run by self serving psychopaths. Bunch of US corporations thought they could clean up and OKed the idea. Russia let it happen because they knew they would be able to recover the Crimea as a result (the US comically thought they were outsmarting Russian intelligence). Europe was totally sucked but now no longer trusts the US in the least and the move is on to free itself from occupation by US forces. The US won a 100 billion dollar debt and climbing (investing 5 billion to do so), the Ukraine is a basket case that no sane person wants anything to do with (Russia was happy to get rid of it, at least the Zaporozhian part and now they are Europe's problem).
Russia is huge and that bit of the Ukraine historically part of Russia and populated by Russians is tiny. The government cares not one whit whether that area being contested becomes part of Russia again or not (it seems inevitable now as those people will never ever choose to be ruled by a government that used artillery on them and that has declared that people living in that region would lose their properties and be compulsory relocated to other parts of the Ukraine to live in government controlled poverty without assets.)
Shit dude, you want to die, just go to that part of the world and declare who you are and what you support, don't expect much from people who have been shelled by artillery. People are dying, it is now some fucking stupid American game, oh sorry, that's right, it is some stupid American game.