Andrew- understood and understand your POV. The slt that i do-in the opening of the form in my lineage there is enough chi gung There are differences in lineage openings.
Joy, I don't doubt it and respect your POV. Certainly the opening sequence and slow movements at the start require discipline over the breathing, which has some crossover with qigong.

From my view the principal aim of the first section of SLT is to drill and enforce correct structure. IMO to try to make one set of movements do too many things is counterproductive.

I still occasionally practise standing post, some "Taoist yoga" exercises I learned while training in IMA, and some breathing drills from Russian MA. I dabble in Astanga as well, though mainly for promotion of flexibility and mobility rather than any qigong-type benefits. Maintenance of joint mobility is important for us more mature practitioners in my view.