underfire,
With the greatest of respect, it is as I say it is, processing ADS-B data in a TCAS solution adds nothing to the utility of the present TCAS system.
It has absolutely nothing to do with security ---- where did you ever get that idea, there is nothing more public than a transponder or ADS-B/C transmissions.
Back to the original question, TCAS is not in any way involved in ADS-B data transmission --- full stop!!
I really sincerely recommend you stick to facts, aviation is not (yet) part of the post-factual world --- but looking at some pprune posters, there is no shortage of potential post-factual (or fantasy world) posters.
Tootle pip!!
PS: DO260/260A/260B is all about varying levels of position/data integrity. Australia "promoted" a very early ADS-B solution (DO-260/0?) to rush a system into operation, and supplied a number of operators with " CASA approved" hardware --- now the shortcomings of that ambition of AsA are becoming evident to many --- some of us have always understood the ramifications, especially $$$$$ to solve a problem that did not and does not exist.
There is and was nothing "unsafe" about what Australia did/does, just vast unnecessary cost for operators.