Small swing + learn efficiency + muscle effort = a good Gienger
After they have the basics of the Gienger figured out, like how hard/far to turn over before releasing, and where in the swing to initiate the turn, they'll be able to add more swing in increments. That way you're actually teaching them a gienger instead of letting them confuse them with something that could waver between a Deltchev and a Gienger.
I guess you could describe my attitude as similar to the concept of teaching a standing bhs before moving on to a ro bhs. Yeah sure, the ro bhs is easier because standing start is eliminated, but who wouldn't rather teach the fundamental bhs first?