I hope this isn't a "feature" but rather an oversight or bug.
First to avoid confusion I'm going to use Starfleet ranks to point out the level the player is in the Fleet.
An Admiral can make an event that allows anyone from Ensign to Admiral to join.
That Admiral can also set it so anyone can edit that said event from Ensign and up.
An Ensign can make an event for other ensigns but not for anyone with a higher rank then they them-self is.
They can't make an event for the same rank as them-self that only can be edited by someone with a higher rank then theirs.
As I said in the beginning, I hope this is a bug and not a feature.
Also the settings Take Over Fleet Event From Lower Fleet Rank & Take Over Fleet Event From Equal Fleet Rank are no longer of any use.
If those could be changed to Allow To Create Fleet Event For Higher Fleet Rank & Disallow Editing Of Fleet Events, then it might work better but not perfect.