Andy wrote:
You should also note that the documentation for current FLARM units
includes a very clear prohibition against use in the USA. One way to
enforce that probibition would be to make the units inoperable in USA

I guess the FLARM people don't care a lot whether you use the device in
the USA or not. The prohibition is purely a protection against liability
lawsuits. So if a pilot or one of his relatives should be insolent
enough and tries to start a lawsuit, they can simply point to that
prohibition and state that it's not their business.