“Rav Schachter (along with a sizable chunk of other Rabbonim) holds that gluten content is what makes something Chametz.”
1)I think this is worded poorly and you really do not mean what this says. If gluten content makes something chometz, then by default all kosher lipesach matza would be gluten free and those with Celiac would have no problems on Pesach. What did you really mean?
2)Besides Rav Shachter, who are some of the other Rabbonim that belong to this sizeable chunk?