Referendums at the barrel of a gun, ones yielding 90% approval, generally speaking, are considered invalid
Yes you are correct: read FR post http://www.freerepublic.com/focus/f-news/3182801/posts
So what would you say about mobs of protesters who force an elected government out and replace it with one of their own? That is how the current leadership in Ukraine was put in power.
The only people saying the election in the eastern part of the Ukraine was not legit are the Ukrainain government and those in the US who want to believe them.