Well... this doesn't have to be as overt as you described.

For example, bypass cap could monitor the line and detect when a security feature to prevent tampering with the device turns on and just disrupt that feature. Or maybe it could prevent the phone from turning off when it should to keep that pesky covert monitoring software running even after you think you have switched your phone off. Or maybe it will cause camera light to be turned off when a particular radio signal is detected so that you don't know you are watched. Dunno.

Just because Bloomberg report turned out to be fake doesn't necessarily mean the attack vector is fake or pointless.

There are millions of engineers/hackers smarter than me and I can imagine somebody will put together a working and useful attack, eventually.