The Bentonite can be skipped in many cases, but it does actually help with the fermentation by providing a nucleation site for the yeast to multiply. It does aid in helping the yeast to flocculate (clump up and fall) when they are done eating the sugars as well. That is a HUGE benefit to aid in clearing. However, there are other schools of thought that bentonite should only be used in whites as it strips color. That might be true with fresh juice, but I don't think it applies to kits, which are quite far from natural juice. So like Wade, I think your friend is misguided and trying to apply wine/grape technology to kits.