"Seems to me that if you are in danger of spinning from a shallow turn in the landing pattern, you are going much too slow."

Exactly. Or, if you are going much too slow you are in danger from spinning from a shallow turn in the landing pattern.

If you are going much too slow you are in less danger from spinning from a medium/steeper turn in the landing pattern because at low speed most gliders run out of up elevator authority before reaching critical angle of attack.