Also - http://www.washingtonpost.com/news/style/wp/2015/04/09/my-bloody-valentina/ Yeah this was some BS, really. She posted random crap on Twitter, big deal. But a lot of Ukrainians in Canada that are largely behind the current Kiev government. So I guess there was the threat of them protesting the TSO to get rid of this "wrong" person, I believe there were similar things expressed against a Russian musician in the US a while ago. Also, consider that our government is sucking up hard as an election is drawing near, and those Ukrainian votes are useful (especially in Toronto for the Tories).
It's not as if she is going to give some anti-Kiev speech in the middle of her performance, some argue she is using her stance as a musician to promote her opinion - but then no one of note can really have a free opinion, heh. TSO really should have just let her play and let the people protest, I assume a patron of theirs decided to squeeze their balls using their donations (the TSO is hurting of late), as well.