Ok, maybe I have the wrong end of the stick here. I assumed they were having to sing a particular football song (Football's coming home springs to mind) which would not be in support of "their" team for quite a few.
Maybe they were singing about football in general?
Of my seven grandchildren, for example, one is "cheering on" Italy and another had been "supporting" Germany. My next-door-neighbour and family were all for Scotland.
I admit most of us would be backing England but really, it's not a neutral topic any more than a political one would be.
Nanof3, please can you post the link?