You need to recognise what kind of airpsace you are in, naturally, and tailor your response accordingly.
You might be just as likely to descend into a airliner flown by crews who are not able to use TCAS correctly. What can you do then?
At least a functioning TCAS system on the other aircraft will recognise that you are TA only - it's reponse will be altered acordingly to (possibly) a more aggressive response, but still a safe one for both aircraft.