The law is not subjective...what people find offensive is.
To that point, songs about terrorists are offensive to some...so the song breaches the act. So, in line with the law...don't sing it at a football match.
Downloading said song does nothing to highlight the law...
Actually, The Lord Advocate said that "this is not about people expressing robust, indeed offensive opinions" adding "this is about people trying to cause trouble at games".
I'm going to need a lot of convincing to believe that Celtic fans are trying to cause trouble in singing this song. That is to say that if The Lord Advocate is as good as his word, this is not, nor can not be criminal.
FFS 
