That's not what he's saying. The section he is quoting is that if the user already consented to e.g. an Amazon Echo listening with a microphone then that's totally legal. Hence it does matter whether or not Google disclosed this to the end user although reading through the rest of that section there's nothing there that would implicate Google if they didn't actually use the microphone in some way. I'm not saying there isn't some law being broken here, but it isn't in 18 U.S. Code § 2511.