I don't think that's correct. He said, "they are a proprietary rope blend made specifically for Tethrd. They are made and tested by an internationally known manufacturer, but they are a tethrd exclusive". Sterling is internationally known (based in the USA) and one of the best rope makers in the business. Not sure that statement means it's cheap Chinese rope. He also said in some other post they were made in the USA. But I can't find it.
EDIT: I found it ... "only some of the products are made in China. Our flagship stuff, (phantom, predator, predator xl, 8mm ropes. ) are all domestic."
Hopefully that's the case. For the price and rating one would hope it is a reputable manufacturer.