No, those attacks still work. Traffic correlation and timing attacks don't actually interact with Tor at all; while a Tor exit relay is a good spot to be in for

No, those attacks still work. Traffic correlation and timing attacks don't actually interact with Tor at all; while a Tor exit relay is a good spot to be in for one (if you're targeting streams that use it), all you need is two vantage points that uniquely identify the network route as a whole. So e.g., the client and server's respective ISPs, or in the case of an onion service, both guard relays. GP is correct though, onion service connections are e2e encrypted, there's no vantage point on the network that sees any plaintext or TLS client traffic. The author of this blog clearly has no idea what they're talking about.