A restaurant has a sign that says “no shirt no shoes no service”. I walk in barefoot and order a burger. They serve me the burger. They had the right to deny me but they served me anyway. The responsibly to enforce their own terms of service is on them. Similarly youtube has the right to deny service to people blocking ads and sometimes does. That does not make ad blocking piracy for all intents and purposes. The onus to enforce their own terms of service is on them. And it would be very easy for them to take more drastic measures but they don’t.

I get that you’re trying to make an argument that morally it can feel like piracy, but it’s just not actually piracy. No copyright was violated. Youtube’s TOS doesn’t change that.