Well, purely in the interests of peace, I am in favour of the decision, too. The Kremlin would undoubtedly bask in reflected glory if Medvedev were to win and there could be issues with unsavoury booing from the crowd. A GS win could be used to stoke up even more bellicose nationalism, 'Russia is Great! Look at our Victor!' etc.
It is sad for the players but unfortunately, there are real life consequences to a dictator setting an entire country at odds with the Western world for those countrymen and women who would rather like to be a part of it.
Ultimately, the victims are not these athletes but those whose lives have been, are being, and will keep being destroyed - until whenever the war ends/Putin's regime stopped.