"
Checking the in-built motion sensors"
The sensors don't store any information whatsoever.
The article assumes full access to the phone - ie passcode/password. Without that, the information is encrypted and inaccessible.
It seems that either because the phone was found unlocked or somebody such as PA knew the passcode/password then there has been the ability to retrieve information, but in the absence of that, there is no way to access the data.
Some high-profile examples of this where even Apple couldn't (or wouldn't) access the encrypted data on iPhones despite FBI requests.
en.wikipedia.org