[usrusr]

I went through this idea in my head reading the sibling speculations about civilian use and discarded the idea: when you have the control surfaces, there's no cost in using them. In terms of aerodynamic inefficiency I'd expect it to be a tie at best, both are disturbances that make the flow worse to achieve an effect.

If they do discover a way to improve aerodynamic qualities with compressed air, chances are civilian aircraft would just switch it on whenever it helps and keep control going through conventional control surfaces just like before.