It's more that I trust Apple to not provide the ability for apps to use the microphone without the user's permission. That's especially true when the phone is off and the app is in the background, there's just no way for the app to use the mic.
Also, the phone was locked and probably face down, so even if the orange dot came on, who’d see it? I read the article. We will pick a totally random topic tonight. Word from a dictionary. Let’s see what happens.