I haven't heard of this terminology before, but, my understanding of a similar process is that it not only dries the wood, it crystalizes any remaining sap within the wood to create a better tone. Think of new (sticky) sap as a dampening effect. (edit- Even though tone woods should be cut in certain seasons to reduce sap, it's still in there to a certain degree.) When I used to build guitars, some makers/players would speak of this. This is what happens to tone woods naturally as they age, and why an older instrument sounds better. As the sap dries out, hardens, and loosens in the wood, tonal properties improve.
For tonal properties, this could make sense. I don't know how it would benefit pool cues though.
another edit- perhaps the treated wood behaves differently when hitting the ball and gives a better feel or something. I mean,between a pool cue filled with sap, or aged wood, sure the aged wood might do better, although I am not at the playing level to appreciate the potential difference
