The problem is the first theft that everyone was too stupid to fight against. Emissions laws established that you don't own your car when they required you to use OEM hardware. The state has every right to test what comes out the tailpipe, but has no right to tell you what you must purchase and install to pass the test. This is what killed the majority of the grassroots automotive hobby and surrounding businesses. You may not like mod car culture, but this was the first step in stealing ownership, just like "free" email and web searches are how an entire industry has the right to manipulate and now own us all by manipulation and exploitation of information.

That said, if the antenna is altered in any way, it simply will not work. Antennas are a funny, fragile thing. The main problem will be when you need to work on the car and the proprietary diagnostic tool requires the car to be on the latest firmware. This will make your car depreciate like a phone. It is neo-digital-feudalism.