Here is my problem with this interpretation...

Is data property? Sure, ideas, concepts, photos, etc can be trademarked/copy-write protected and have some degree of ownership, but I'm talking at a much lower level here... Is the particular configuration of memory on your phone a piece of property? If no, then no property was destroyed by wiping the phone. All of the storage and memory is still intact and functional. If yes, then we must look further...is the position (not the switch itself) of a binary switch (like a light switch) a physical thing that you can own? Would you consider it destroyed if it was switched away from it's original position?

I don't think you could charge him with destroying property... Destruction of evidence maybe, but the property is undamaged and functioning normally.

Other arguments. The cop actually destroyed the data. Or, defendant claims he did not know the cops would use the pin to wipe the phone, and that they just wanted to know what the PIN was.

I wouldn't say there is enough evidence here to prove beyond a reasonable doubt that this guy destroyed any property in response to a search. He didn't destroy anything, what was destroyed is arguably not property, and he may not be aware that his duress pin was going to be used on the device in the first place.