An employee at Path might very well decide to start looking through that data. There have been other cases where employees gave in to temptation to access someone's data. Imagine for example if a celebrity is involved and someone decides to leak their address book.

Now one would hope that employees wouldn't have unrestricted data to this access, but one would also hope Path wouldn't do this in the first place. The fact that they collect all this information in the first place, unnecessarily and without consent does not inspire much confidence in their internal safeguards for access to this data.

Also, if anything were to happen to the company, it's hard to know what hands all that data will end up in.