Hi Chuck,
The product in question here SuperThrive, itself has NAA which is scientifically proven to help with root (lateral) growth. The link to the PDF is about B-1 added to any product and it's role in plant health. Which I agree is disputed, not the auxin NAA which is scientifically proven.
Naphthylacetic acid (NAA) is also a commonly used auxin and often the active ingredient in commercial
preparations. NAA tends to be toxic to seedling root development, as it inhibits primary root growth and
enhances lateral root growth. This latter activity may account for NAA’s success in regenerating roots of
transplanted and root-pruned trees. Like IBA, NAA apparently suppresses crown growth, which also may
redirect resources to the roots.
I think perhaps marketing is involved, people know the health benefits of B1 in their diet natural assumption good for plant too, easy sell. Who's going by an auxin NAA?
http://en.wikipedia.org/wiki/Superthrive
So I think there is some confusion because the researcher is not saying Superthrive with NAA in it is not beneficial but that B1 is? Superthrive is not the only product claiming to have B1 to support plant health.