The suggestion utilizes existing mechanics that do not create a 100% protection zone. The zone isn't always active as in there's an event there so once it ends the zone deactivates and what you have is a simple sphere.

Turrets are an unnecessary and inappropriate protection for player "events."

The "simple sphere" is all that is needed or appropriate. The rest of it--advertising, registration, etc.--is simply a waste of development resources.

If the devs ever find time after implementing all of the far more important aspects of the game, I wouldn't find this to be a waste of time.