The U.S. Department of Agriculture found benzethonium chloride in NuriBiotic GSE. It concluded that "It seems unlikely that benzethonium chloride is formed during any extraction and/or processing of grapefruit seeds and pulp." The obvious implication of this is that the manufacturers of NuriBiotic added benzethonium chloride to their Grapefruit-Seed-Extract to make it work.
The question remains whether the amount of benzethonium chloride contained in effective Grapefruit-Seed-Extract products (8% seems to be a ballpark figure) is hazardous. I am not aware of reported health issues with users of GSE, but obviously it is a concern if taken at high enough doses for an extented period.
Also of concern is that now that this 'practice' has been brought to light, will some or all of the companies concerned stop adding benzethonium chloride? If so, will Grapefruit-Seed-Extract products suddenly stop working?