It has never been discussed widely in the media, but in the same manner Russia can argue that people in Donbass have been killed for 8 years by Ukraine. Isn't that the same kind of justification to military intervention?
If it’s not been widely discussed in the media yet you’re familiar with it, then what “objective” sources are you looking for? Ones that say Russia’s invasion is justified because of that?
Their stated goal for the invasion is to “demilitarize” and “denazify” the whole of Ukraine. Ukraine has a Jewish president.
And yet there are neonazis in the Ukrainian military who attack Russian-speaking separatists in the east and who were in the vanguard of the 2014 revolution. It's wacky and hard to believe but a conflict the large is never black and white.