The Secret Service has its hands full trying to stop counterfeit currency, mostly $100 notes. I doubt they will have much interest in putting manpower on stopping counterfeit US quarters and other low-denomination stuff. Realistically, their job is to protect the integrity of our currency so it will continue to be accepted without question; a few counterfeit coins have little impact on trust in the billions of US Federal Reserve notes in circulation.

I also suspect the news articles on the fake PCGS certified coins are using sloppy language. What is really counterfeit is the product of a US business... PCGS graded and certified collectibles. If the feds ever did get involved in the faking of this product, the Chinese could easily just use lower graded genuine coins in their homemade holders.