The fact conversations like this take need to take place is in itself worrying. Incidents of minute's silence and national anthems being disturbed by a minority of idiots were rare and barely drew any attention not so long ago. These days they seem far too common, possibly highlighted and encouraged by the influence of social media etc. As others have said, there is a time and a place for complaints of perceived injustice, booing, political and disruptive behaviour, however deliberately sabotaging a national anthem or a minutes silence where there vast majority want to respect the moment is neither the time or place.
I have been sat in the middle of such incidents when a few fellow "supporters" around me decided to be disrespectful at the wrong time, it created an uncomfortable toxic atmosphere where said supporters spent 2 hours abusing each other at every opportunity, completely avoidable and unnecessary if said people had shown an ounce of respect and kept their mouth shut for just one minute!