http://www.theglobeandmail.com/globe-debate/columnists/why-the-tso-set-a-terrible-precedent-by-barring-pianist-valentina-lisitsa/article23845288/

The bar on Ms. Lisitsa puts the TSO in an impossible position. If other groups come knocking, Mr. Melanson must now, for the sake of fairness, consider each objection to each musician. If he rejects the objection, he must explain why. He will have to say, for example: We looked at what that Israeli pianist said and we didn’t think it was as bad as what Ms. Lisitsa said.
...
By taking sides in the dispute between Ms. Lisitsa and her critics instead, Mr. Melanson has invited a world of trouble into his concert hall. The arts world is full of opinionated, often eccentric souls who express themselves in intemperate ways. Who is to judge which is to be banned and which allowed?

Not, certainly, the Toronto Symphony Orchestra.