is that ignoring an RA is significantly more dangerous than that aircraft operating in TA-only.
Spot on, can't believe so many people are having trouble with that concept. Pretty obvious that there are situations in the military world where you would be unable to follow an RA, civil aircraft set TA in engine failure cases for the same reason. As you rightly point out setting TA means you are still fully interoperable with other TCAS equipped aircraft which can generate their own RAs if required.