Perhaps you are mistaken? I'm certain only users within the Moderator group or above have that power.
His threads are pinned because a moderator pinned them. He didnt pin them himself. As twin retro said if someone requests a thread to be stickied we will consider it and pin it if we think it's useful enough.
I would hate to see a day when non-staff can sticky threads. The horrors of what the EoF would look like!
