The idea is to prevent anything serious happening.
At what point has there been any hint of something serious happening. Were people terrified of being severely injured by one of the handful of tennis balls thrown?
On that basis can you show where action was taken against ACL for the pitch invasion following the charity match or against Wasps when they had a naked pitch invasion?
Not what you want to hear I know but the council can close down any business that requires a licence from them.
Councils can do lots of things, that shouldn't mean they can go around doing things unchecked and be allowed to get away with actions that are clearly based on a grudge.
So again, show me a single council who have ever threatened to have their local football team play behind closed doors? You're clearly trying to defend this, I wonder why?
This is the key isn't it. If this was reasonable action by the council there would be numerous instances of similar action to refer to but there isn't.
Lets looks at what's actually happened:
Whistles - no problem there from a SAG perspective there
Tennis balls - no problem there from a SAG perspective there
Wembley celebration - shouldn't be an issue here as I can't think of any single instance where a teams fans celebrating on the pitch has drawn any sort of negative response.
So that leave the protest on the pitch during a televised game in the middle of December. Why have they suddenly decided that's an issue now, there's been no repeat.