I think the way all comercial modules do the choke is this way: when they receive signal from piezo and a shortcut (or resistor value near 0, not infinite) from sleeve of jack, they trigger the edge sound, but when they see a shortcut lasting more than X miliseconds they trigger a choke event, independently from the piezo. Take into account that when you grab the cymbal to do the choke, you produce some (small) vibrations on the piezo, so I think it is not 0+1=choke.
Well, dmitri should through us some light in this matter