> There's really no Constitutional or statutory argument against requiring ADS-B.

You could argue it's not a very good one, but it does exist:

"This rulemaking provides an exception to ADS–B requirements, removing the transmission requirement for sensitive operations conducted by Federal, State and local government entities in matters of national defense, homeland security, intelligence and law enforcement."

https://www.govinfo.gov/content/pkg/FR-2019-07-18/pdf/2019-1...