Looks interesting - but if you can snap it on as threaded rod at the middle with finger pressure, and the two mating 'locks' are just tight enough to allow this, the centripetal force of spinning it with air to turn will potentially launch the two halves in opposite directions with a rather scary escape velocity. "INCOMING!!"
You would have to make the mating locks rather large enough to be permanent and spin it onto the end of the shaft - and in that case why not make the nut out of a solid piece of material and skip the split?
Or make the two halves with channels on both ends, and two 'dogbone' keys to assemble onto the shaft. Then you have to add a ball detent to each nut-half or dogbone to lock the keys in place...
-->--