Part of the API request sent to Facebook at the time of authorization specifies which permissions you want the user to grant. I have not inspected his code but

Part of the API request sent to Facebook at the time of authorization specifies which permissions you want the user to grant. I have not inspected his code but I think it should be possible to modify those permissions before agreeing to them. The side effect of this is that the webapp you are authorizing may work unexpectedly when it cannot access services/functionality that they originally indicated that they wanted you to agree to. Short answer: your OAuth token includes permission status so yes, this should work.