c) Control Advantages
Immediately (and initially) searching his rear waistband after being cuffed will curtail later uses of force should he produce a concealed weapon—many officers have been killed with hidden weapons not found during waistband and subsequent body (crotch) searches.
Maintaining a hold of him at all times is wise should he try to fight or flee from you upon your getting close to, or while discovering his hidden contraband.
Rolling a prone person from side to side is a good tactic, but feel free to search him again in the standing position to ensure that you did not miss anything.
You can always do more detailed searches by removing bulky clothing, shoes, etc.; jail staff will likely let you know if you missed something of obvious importance.