What..?
Ok, so let's swap the term racism for something else, nationalism. It's no different to saying you have to support white people instead of blacks. Why should your place of birth (which is simply an accident of chance) restrict who you can and can't support?
I'm struggling to see how this is a moral high ground or touchy feely argument that shuts down debate. If you could explain the difference please enlighten men, but don't brush it aside simply because it's logically sound and counter to what the touchy feely stuff we get taught in school.
You are free to support or dislike whoever the hell you want, I'm also free to tell anyone who actively boos their own countrymen that I don't respect their decision.
Nationality and Race = Apples and Oranges....last time I checked the "white race" dosen't send me social assistance checks or provide me health care...nor does it come to my aid when Canada is attacked. Many people do change their nationalities as well by immigrating or emigrating(though I acknowledge that these oppourtunites are different and somtimes limited by circumstance) as well many of us have the oppourtunity to change the nations we live in by molding them, look at the changes in South Africa in the last 20 years as a perfect example. "Nation" is a maluble concept. The only people to use race in this way have been proponents of Eugenics who have commited some of the most awful atrocities in history.
I also don't understand the "which is simply an accident of chance" welcome to the human race!! We are all restricted by accidents of chance, I won't be entering an NBA court anytime soon but using your logic I should get them to change the rules so the basket is only seven feet high. I could sit and whine about it all day or I could go play another sport or attempt to hone some dribbing and shooting skills to compensate, much like the people who would boo at Newlands when South Africa is playing New Zealand could get off their ass and make South Africa a better place if they don't like it or actively attempt to emigrate, rather than sit around and cry...."ooohhhh I wish I'd been born in New Zealand". It's a lazy and petty thing to do, I acknowledge there are historical reasons for the NZ vs. South Africa support, but none of the current players are actively responsible for what happened two decades ago. In some cases they are representations of positive change.
Likewise you are already changing the "terms" of your debate it's already gone from booing(which is an act of active dissaproval) to "supporting" which are also two entirely different things. I saw quite a few Italian "supporters" many of whom were Canadian citizens at Italy vs. Canada last June, they supported Italy by cheering when the Azzuri did well, and at most there was some cheerful banter between opposing fans, they didn't come in and actively boo their own countrymen nor harass the Canadian team as it left the team bus. Many got up and cheered both teams off the field, and some were wearing both Canadian and Italian colours.
Edit: When I accused you of "poisoning the well" in your first post, this was against your statement that anyone who had a different opinion on this was "borderline racist". Laying out something like that changes the nature of a debate, since you insinuate that anyone that disagrees is a morally inferior person. Politicians and academics LOVE to use this kind of language, eg "Anyone who dsoen't support our Internet surveillance bill is for child pornography"( a Canadian politician actually used this...even more hilarious since he got a teenage babysitter pregnant some years ago).