Maybe I'm just cynical, but it sounds like CMG's real crime here was "defrauding innocent advertisers" and not "spying on people".
I think it's a realistic form of cynicism. The system tends to not do a lot to materially protect consumers and individuals when it comes to claims of falsehoods and the like, but the moment there's potential to cause financial harm to a corporation then suddenly there's plenty of action.
This outcome doesn't particularly surprise me though. I had a hard time believing the original claims to begin with, in spite of anecdata of friends talking about a thing only to get it advertised to them a short time after. I do think it's technically possible, but I don't see a way for the impact to not be noticeable. Either they're using on-device processing which would wreck battery life, or they're streaming audio to a server which even at a fairly low bandwidth would still be noticeable to users who are data-conscious (while still hitting battery life). Perhaps there are clever ways to mitigate that, get it lost in the noise. But I'm still dubious. Give it a bit of time though, and that could easily change.
Maybe by then we'll have a government actually interested in siding with the average individual. A nice dream.