How is that any different than a prompt engineer other than the degree to which "...actively participates in the performance and creation"?
A conductor has control over the tempo and cadence of the entire piece. They can choose to pause the entire performance on the spot and then resume right where they left off. They may adjust sections to play louder or quieter based on weather and acoustics.
And that's all during performance. There's work needing in at the bare minimum arranging pieces based on the band.