I've heard of this, the "air pivot". It's all pretty subjective.
Any pivot method that doesn't have an exact pivot point that can be used for every shot is a very subjective method of aiming, requiring a lot of trial and error. I mean, the only way to pivot perfectly onto the correct shot line everytime is to be able to recognize the shot line and the exact pivot needed that puts your cue on that line.
All of these pivot methods seem about as time consuming to learn (or develop consistency) as ghostball or traditional fractions or contact point aiming, so why pivot at all? In other words, since you have to develop the ability to recognize where the cue needs to be in order to make a pivot work out just right, why not just step right in and line up with the recognized shot line without pivoting? Some will say they don't have to know or recognize the shot line, that the pivot takes them to it, but it doesn't, not everytime. Sometimes it just works out, like when a fractional aimer just happens to be on a dead halfball shot or a straight in. It happens a lot, but you must learn to recognize (through experience and practice) every other shot that doesn't happen to line up perfectly for a halfball or straight in.
It's no different with pivot aiming. It'll work out great for some shots here and there, but for every other shot you must work with the pivot points in order to make it work out, which is why it takes a lot of practice -- because you have to develop the skill of recognizing when it looks like you are lined up correctly.