glider aerobatics

Question concerning aerobatics in glider category. We have 2 Grob 103s, a 103A Twin II and a 103C Twin III Acro. The Airworthiness Certificate for the first just says Standard Category Glider while the AC for the Twin III Acro says Standard Category glider, Aerobatic.

Now the question. The Twin II POH says loops are among the approved maneuvers. Are loops legal maneuvers in the eyes of the FAA, in a non-acro certified glider? Obviously, the Twin III Acro would be expected to be loop legal since loops are not specifically prohibited in its POH and are in fact listed as an approved maneuver. Are gliders that different from airplanes such that the POH can "approve" aerobatic maneuvers in "vanilla" Standard glider category aircraft? I was under the impression that the FAA considers anything over 60 degrees of bank or 30 degrees of pitch, (except for spins), as aerobatic and requiring an aerobatic airworthiness certificate unless it's a special AC such as experimental amateur built where limitations are listed separately in ops limits. The glider pilots I've talked to seem to think as long as the POH says they"re okay and there's no AD extant that prohibits them, then you can loop a standard category glider such as a 103A Twin II to your heart's content. What say you?