Wouldn't it still be possible to guess a lot about the design and find potentially exploitable mistakes? Or to build defects into the traces so that they fail in use due to vibration, temperature, or poor mutual inductance? Transmitters do seem far too difficult to get working in a shielded environment and prone to discovery.

I wouldn't trust their ability to monitor and properly neutralize the etch back.

All Chinese plating is crap, always rushed through rinse and usually contains residuals.

Can't believe no one mentioned this, a ticking time bomb for corrosion and failure.