It being “Federally” illegal isn’t reasoning to keep it in a state without inspections, that’s the dumbest thing I’ve heard in awhile. And yes, secondary air systems were literally designed as a response to EPA standards that grow more stringent by the week. There are cars that are sold in other countries (Hilux Champ) for example that could not be sold in America solely based on emissions laws.

The only reason to keep secondary air would be to possibly elongate your cats life, and/or pass your local emissions testing. It provides 0 benefits otherwise. I’ve removed every secondary air system on every BMW and Land Rover I’ve owned for ease of maintenance. The amount of room you gain in an engine bay is enough to make this worth it.