The explanation offered by Google support staff was that since his address details differed, billing information with Google wasn't current and hence the user's purchases could look fraudulent.
The user in question does not know for sure that this is the reason; during his interactions with Google support to find out why he had been locked out, he was told that "It is our policy to not discuss the specific reasons for an account closure."
This, apparently, is official Google policy.
But after this time passed, he was told that the account would not be unlocked and Google would not tell him why.
He was advised to abandon his old account and start a fresh one.
However, this meant he could not use the credit card that he had used on the old account and would have to obtain a new one to continue using Google's services. All his previous purchases would not be transferred to the new account, he was told.
An email he sent to Google support resulted in the following reply: "We understand you would like your account reinstated. As previously stated, per the Google Payments Terms of Service, we reserve the right to change, suspend or discontinue any aspect of the Services at any time, including availability of the Services or any Service feature, without notice and without liability."