Fair point, which opened up a thought. After thinking about it, I would support clapping for those connected with sports or performance and silence for the military. Sort of along the lines of sportsmen and football supporters feel more honoured by applause in life and honouring them in death should not be any different. Not quite a fully thought though reply, but I get your point and I have changed my view.
Another point as well is that in an outside environment it's hard to control external factors, so their could be loud exterior noises in some places like aircraft, birds, alarms etc disturbing a silence, quite apart from controlling thousands of people inside.