I don't think "selective" is really the right way to think about it. The people who wrote Tornado Cash remain in federal custody for money laundering, which I'm pretty confident they'll be convicted of. And anyone who uses the service to do money laundering would presumably be prosecuted as well, if the government can find them. Coinbase has just identified a regulatory loophole to prevent the service from being shut down.

(Is it possible to use Tornado Cash just for privacy? Sure, I guess, but I'm skeptical that many people do. The pooling mechanism makes it inconvenient to use for ordinary purposes with the pretty explicit purpose of helping money launderers.)