I think the scooter was involved with Max's fall. I think it's possible Max was using the scooter in some kind of posed, balanced position on the newel post, or railing. Whether or not that meets the definition of planking is up for debate.
If Max was holding onto the handlebars and fell outward and head first, the scooter could have become entwined in the chandelier, and with the weight of Max, pulled the hanging chain apart. Particularly if he was balancing on the railing and/ or newel post. There was a "missing link" in the chandelier chain that was photographed on a step, and subsequently lost by the investigators. Dr. Bove was unable to examine it.
There are a number of scooter scenarios and "showing off" (stationary or in motion), or "still" planking tricks that can explain a head first impact that also takes down the chandelier. Consider a "spinning" trick involving the scooter and the newel post, for example. Velocity and momentum are certainly possible there, right?
Dr. Bove, unfortunately, was only paid to run the numbers on the Gomez diagram and Dina's imaginative, but highly unlikely scenario. There are many scenarios that could explain Max's accidental fall.
Added:
Check out the spin move at 33 sec mark.
Razor Scooter tricks - YouTube