Does he want to stay in the space industry? Consulting in a specific technical field like that would be more learning on the job. Firms like SRI and Aerospace Corporation have a technical focus, but generally more on the engineering side than math.
Having said that, by Dec 2023 a bunch of the current enthusiasm may have run its course and space might not be a happy place to work (though financial firms could have a field day restructuring a bunch of things).