I find this study to be essentially meaningless so far. If you want to build an Al frame that's comfortable you make it with relatively small diameter tubing and slightly thicker walls (such as the old Vitus and Alan frames). OTOH, if you want an Al frame that's stiff at the sacrifice of comfort you make it with large diameter tubes and thinner walls (such as the early Klein and Cannondale frames).

The Vitus/Alan aluminum frames were touted as being more comfortable but relatively 'whippy' compared to typical steel frames of the time. So Klein, and shortly thereafter Cannondale, designed their aluminum frames in the opposite direction - for high stiffness. But they then got the reputation for being harsh. Such design choices can be far more significant that the inherent material properties of Al vs. steel vs. carbon fiber.

This test just looked at three individual Cervelo frames and their conclusions only apply to the design choice made by that one manufacturer in making tubing sizing and shape decisions that influence the stiffness vs. comfort tradeoff.

The study objective appears to be to eventually (with much more extensive testing) see if performance is impacted by vibration levels and I think it may be able to give some insight in that area. It could also give valuable data about the vibration characteristics about specific bike frames or other components. But it doesn't seem to be properly designed to evaluate the effects of inherent material properties of different frame materials, nor is that listed as an objective of the study.