The theory is correct, to stop vibrations from propagating you need to have a big difference in density between materials. The resonant frequency depends on mass, if you change the mass you change the natural frequency it vibrates at. In practice, this is more of a romantic idea... There are a lot of vibration modes occurring when you strike a ball, and how the blade vibrates is dictated by the construction, materials and shape. If the vibration you are feeling is for example at the tip of your index finger, changing the handle will do absolutely nothing about it. I've made blades with low density, hollowed wood, which had virtually no vibration, but I've also made blades with solid dense wood handles that had a lot of vibration. I've also swapped from one to another on the same blade without a perceivable change in feeling.
In the case of that specific blade, the biggest reason is that it has an extremely light Ayous core. Low weight is nice and all, but it has consequences on the feeling of the blade. An inner fiber blade with 83g and a balance of 2.4cm isn't common at all, but that low density core is also less stable. If the handle pieces were completely solid then I would say that there wasn't that could be done, BUT! they are indeed slightly hollowed. I still don't think it will make a big difference, but a dense handle might help to tame some of those vibration modes.