I dont think thats her own disicion. If she drops the show because she doesnt want to be booed, she isnt a professional at all, thats not even respectful to VS. and because she said "see you next year" it means she will return next year, do you want to select a model who drops you last minute, especially she is one of your highliner? I dont think so. So it has to do with the VISA or work permit.
Katy Perry got banned because she was in Taiwan, holding a Taiwanese flag! China is in conflict with Taiwan for so many years. If you got banned for just holding a flag, you will be banned forsure for making fun of Budha! Thats what I think.