Quashing free speech in Oz

If you are planning a trip on Qantas in the near future you might want to wear a jumper over any politically minded tee shirts at least until you take off. Allen Jasson, an Australian living in London, was barred from a Melbourne to London flight because he was wearing a "Bush is a terrorist" t-shirt and plans to sue the airline. The airline says that they refused to board Mr. Jasson because his shirt was "a security risk or an item likely to upset passengers".

I wonder if they would let you on with an "Osama is a terrorist" t-shirt or even an "I ♥ Bush" t-shirt? The later would certainly upset me (and most right thinking individuals).