From what I've seen in other markets, there isn't much they can do. If there is a demand for it, China will supply it.
As an extreme example, most of the import fent comes in much the same way as our peptides. Think about that when you drive by your next homeless encampment.
As you said, it only affects compounding pharmacies. And compounding also sources their peptide products overseas. Possibly with more official-looking sources and sophistication.
I think Big Pharma want's to plug that hole in their revenue stream. They're hoping you're going to go to name brand now and not turn to the dark side.