That's entirely true and it's one reason why I hesitated before nitpicking. That said, I think that the distinction should be properly made when someone is discussing a new way to sling data over a network from the application layer. If the author had written what you'd written, I'd have let my reply go.

(Even so, it's not that the "TCP session" is encrypted; it's that the transport-layer security mechanism encrypts the payload of the TCP session. The metadata for the session--the respective IP addresses, sequence/acknowledgement numbers, and so on--is still in the clear. I realize that, at this point, I'm being quite pedantic but I'm a networking person at heart and I want software developers to better understand the infrastructure that's being used.)