The linked thread doesn't contain any information about what these people actually blocked or in what way they can't use other Google services anymore.

If they blocked DNS resolution and SSO is causing trouble, like people here are speculating, then the fix is unblocking accounts.youtube.com.

If they blocked connections to YouTube's IP addresses they've just blocked most of Google, because YouTube is served from the same (relatively small) set of IP addresses as a lot of other services.