After the threat is assessed, I dont see why I would need to reholster my firearm in a hurry. Simply look down and at my holster and reholster my weapon slowly, its that easy.
I think the overall point has some merit. However, to act like any number of things will be just "that easy" if you are involved in a truly life threatening situation, particularly one where you may have just killed someone and/or been seriously injured yourself, may be a bit naive.
I hardly practice reholstering
The above is even more true for a skill that one spends little time practicing.