It is just their opinion and has no basis in fact - reinforced by the fact that they can never qualify why it won't work or why it is a huge risk. Unfortunately there are a few people on these forums who endlessly repeat their 'CS6 will not work because it is not supported' mantra and 'it's a huge risk using CS6'.
Sara, if you do sort out your licence then there is a good chance CS6 will actually run on your brand new Mac.