Zephyr has always been and should always remain an open, public landmark. There are spas and shops with a few items that can be purchased by visiting only this location, and no one should be able to inhibit anyone's ability to visit Zephyr or any of the public landmarks. I am not saying you would do this as I am sure you're not the type who would be despicable and hateful as to abuse hosting privileges at a public landmark meant for ALL members to enjoy... But there are some who would and this would cause even more drama as there are some who do abuse open hosting zones and remove people just because they can. I can say this because I speak from experience as I have witnessed people doing this, abusing hosting privileges at open hosting zones.
If you really, truly wanted to hold an event in Zephyr you can already do so by placing an activity flag. It will appear in Happening Now. You just won't be able to change permissions, remove people from the area, or send invites.