Eh…it’s not as glamorous as you think. The ad is recorded, Google devices are nearly always connected to the Internet, and the voice recognition piece is largely cloud-based. All Google really had to do was a quick hotfix that checks the incoming sound “fingerprint” against the ad. Since it’d be nearly identical every time, it’d be pretty easy to filter out. Dollars to donuts, if another such commercial comes out, devices will react again for a short time.