I understand all that, and am very clear that no causality can be drawn at this point - what I was a bit concerned about was the "fucking stupid" behaviour where people - who subsequently tested +ve for CV19 - had attended parties celebrating the league win.
I dont think for a minute that these people caught it in George Sq (like you I think the outdoors is basically fine) or even the parties themselves.
Given the timeframe its more likely they caught it ahead of the Sunday............however the rather obvious concern is that those infected nuggets (be it only half a dozen as you mention) went to parties, sang loads of songs and infected their pals who then go home etc etc ......well, you get the picture?
I would have thought that this was really obvious, sorry if I am telling you something you had already worked out.