The data is stored on Google's server, therefore can be accessed by the NSA, FBI, CIA and by the However-Many Eyes' intelligence agencies. All of those places can be breached, can accidentally leak your data or can even change their mind about keeping your data secret. And given that they're most likely storing this data indefinitely, that chance is 100%. It's going to become public at some point. How long it takes until that happens and how accurate/harmful that data then still is to your current life is a different question. But personally, I see no reason to unnecessarily risk that.