Replying because I don't think your post deserves all the downvotes, even though I think your argument is stupid.
TBH, my first thought when I saw the "notice of extortion" letter was that it was a joke. Not a particularly funny one for the restaurateurs, but perhaps someone's lame idea of a prank that got a bit out of hand.
However, as others have pointed out already, it is most definitely a clear-cut case of extortion whether or not they have any intent of following through on the threats. Just as robbery with an unloaded gun is still robbery and threatening with a deadly weapon: nobody knows whether it's loaded, so they have to assume it is. In that case the induce fear and panic is quite real. People have been known to have heart attacks in such situations. In that case the the perpetrator has committed a homicide, regardless of intent.
It's also not a very good way of winning hearts and minds if education is the goal.