No, it doesn't. It says that white people did use blackface to portray blacks but there were also black people in the film. If you'd like me to find other examples of blacks/Native Americans/hispanics portraying roles that are racist I'd be happy to find them for you.
Did the actors know about it or were they tricked into doing it? Did they have a choice?
Irrelevant also, you are just lurching from one poorly thought out argument to the next. Why is it so important for you to defend people's right to be racially insensitive, and paint those that find racism offensive as being PC whiners?
Anyway, the participation of Black extras in anything considered to be racist is certainly not any indication of whether it actually IS racist or not. And nothing you are suggesting here demonstrates otherwise, you are simply attempting to tie the conversation up in knots.
This advert in particular (unlike any of the material you have posted to attempt to justify it) was wrongly perceived as being racist because it seems to portray blacks as noisy tribal folks who are irritating a single white guy, who discovers he can quiet them merely by giving them Fried Chicken, simple folk that they are. Whereas in fact, they were all black simply because Australia was playing a team from a predominantly dark skinned country, and the joke was a running one applied to many situations.
That's what you are defending here, and that says a lot about your attitudes.