That seems like an amazingly impractical route to exploit a device.
The one solid example they gave was, if an app already uses the accelerometer to "do something". But... some other nearby device would have to know that someone was doing that on their phone, and precisely when to generate the sound. OK.
I can see how you could manipulate an accelerometer and decode that as data to then execute a function. But that would tend to presume that the device would have to be exploited already, because some sort of software would have to already be on it to decode that data, and then do the malicious activity.