Thank you. I can see why he would be worried. It's one of those things that's unlikely to happen to "you", but is probably only a matter of time before it does happen to someone type of things.
I think one has to look at it through the lens of the Chinese suppliers supplying these things, if they're already breaking the law by doing so, then what's the odds they aren't offering other things that could be dangerous. I'm sure if it does happen, it wouldn't be on purpose - but the people dying every day from fentanyl being in things is very rarely, if ever, on purpose too.
And this isn't meant as a put down to the Chinese suppliers. It's important for people to remember that even though these things are so normalized in certain circles, they are still illegal in the US and on the Chinese side as well. So expecting a supplier of these things to not possibly dabble in other things would be like the old analogy of why rob a bank and leave half the money.
The testing the FDA did on the suppliers in the US showed a lot of frauds - in the sense that it wasn't Reta, but other GLP drugs, which would still do similar things as Reta. The question there is was the US company intentionally misleading their customers or was the Chinese supplier misleading the US company - but the end result was the same in that the person wasn't getting what they thought.