How does deleting a photo differ from destruction of property? We’ll assume that the delete is a permanent one.
A photo on the memory card and the memory card itself are both tangible items, no?
That was my thought as well. If the club rule was changed to: If you take a photograph inside the club with a polaroid camera, that polaroid is destroyed along with whatever other polaroid pictures you happen to have on your person. I’m assuming if the example in the OP is a legally enforceable contract, then this one would be as well?
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I think it’s interesting as cameras are getting better and smaller. I’ve seen them the size of a pen. The real next issue to come up is, who has the right to do anything with my image?
For instance I’ve seen site where people post fat people struggling to exercise at Ballys or other gyms. Surely those people at Ballys didn’t come there to be mocked in a public forum. I know in some states you can’t photograph someone without permission but that is usually limited to places like the locker room.
And certainly there would be a difference if the webmaster was posting a pic on a free site versus a site you pay for and making money off your pic.
This will be more interesting as time goes on, as with red light cameras, and cameras all over street lights in high crime areas, people will get so used to it they won’t care anymore.
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The legal/illegal discussion is interesting, but here’s another practical consideration: what if the device has password protection? Y’know, like a Blackberry.
“Hand it over!”
“Sure, dude, knock yourself out.”
“…What’s the password?”
“Blow me.”
“How’d’ya spell that?”
Or you could just slide your photos to another folder on the thing. How is a dumb bouncer going to be able to figure out where the photos on the thing are anyway?
The secret command to delete all files on any such device is “hammer” 
Hmmmm.
This could also provide adrenaline junkies with a nice “out” to beat up facility security.
Just have to take a dozen of your closest completely insane friends… then wait for an illegal attempt at camera confiscation.
Sorry about the delay.
I don’t think the duration of possession matters in a matter of robbery.
Take my property from me, and you have already committed a crime. Giving it back to me doesn’t change the fact that you have committed a crime. How long you kept it from me has no bearing on the fact that the crime was committed.
Tris