I didn't realize you could use CSP for preventing exhilaration now! How did they close the WebRTC loopholes?

They haven't. That in the spec stops short of actually saying that it will stop all exfiltration. What it will do is make it harder because you'd have to put the data in a subdomain or in a username/password. It also could make it hard to deny that an attempt to exfiltrate was deliberate.