They know very well that they can not prevent access to a website like piratebay with the existence of VPNs, Tor and even mirror sites. So instead they let it run and target the users who download pirated stuff through their ISPs while heavily censoring the site and all related links on the internet like the hundreds of thousands of URL takedowns by Google.
It's the same with bitcoin. They know very well that they cannot prevent bitcoin adoption and if some day they decide to ban it, they will start targeting the users. For example if your ISP realizes you are running a full node or connect to an Electrum server they will send you a letter of warning first and then shut you down if you insist on continuing it. BTW that is similar to what they do to battle piracy which is another P2P thing they cannot shut down.