Technically, the way I read it, his property is NOT being used. He is objecting to a use on property where he has a shared easement right.
He's on strong footing, but he's also being a dink, and it's worth pointing out he is controlling a space that is not exclusively his to control. It's a quasi-public space.
the event was on private property [not Simon's], the mall was able to assert authority on the matter due to reciprocal property easement agreements.
>>>> Technically, the way I read it, his property is NOT being used. <<<<<
Whatever rights he has are sufficient to stop the event.