I think you're right about Ueshiba not exhibiting the "whole-body spiraling of Chen taijiquan." To me that's neither good nor bad; aikido and Chen taiji are two different arts using different approaches to body methods (Chinese shen fa). And your remark about limited relevance/benefit of SREs to aikido is a good caution for aikidokas looking outside of aikido for "internal" exercises.
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"The internal connections need to be conditioned and the coordination to move in accordance with these connections needs to be developed. . . . . Once can contract the frontside of the body with the dantien/hara as center to 'close' the body. One can also contract the backside of the body, again with the dantien/hara as center to 'open' the body. This opening and closing of the body can only be done if the internal connections of your body have been conditioned sufficiently to guide the movement. And if you allow these connections to fully define your movement, you'll get the typical spiraling movements of silk-reeling." (bold added for emphasis)