Do keep in mind that the US Gov sponsored the Airmail program for
multiple reasons - of which 'jumpstarting the aviation industry' only
one, if not a side effect.

Hmm, didn't find much about this in a quick web search. I found a few
mentions of "Kelly Act", the text of the act, and the interesting ways
it was amended later, but not much about the motivations. I don't
think the Congressional Record is online from back then, for
example...