While in a simple test this might work, for a reasonably sized layout, it's very doubtful that this would be effective. Larger layouts frequently have issues even with the track signal connected, relying on weak capacitive coupling would surely exacerbate that issue.
FWIW, I've had limited success running stuff with Legacy on my test bench with no connection if the layout track is energized. It's somewhat spotty, but even 10-12 feet away under certain circumstances it will sometimes work. However, that's not the basis for a reliable layout with TMCC/Legacy, at least IMO.
