Are you thinking of a hub and spoke architecture where the Sat is a trusted third party? That violates e2e security, as the Sat is privy to any communication it proxies (although this might be a desirable properly for some govts).

An initial draft of the post focused on the authentication part, but that's easy to counter, e.g., www.amazon.science/blog/qkd-and....

Satellite QKD is also point-to-point physical links (just not wired), so that shouldn't impact the scalability argument.