Having GMP grade extracts as the API inputs doesn't necessarily make the finished manufactured drug GMP Compliant though.
That would depend where it was manufactured and whether that manufacturing facility was also GMP certified. You are being disingenuous using that quoted statement as "proof" their products are in fact GMP compliant. I'm sure you understand the difference.
Do they have a GMP Approved manufacturing facility or do their contractors? Or maybe they dont....?