In many of our emergency procedures, we have an item that tells us to select TA only. For instance; engine out performance when heavy. I think it would be appropriate to select in most any real emergency. After all, you are in the midst of trying not to crash, why put added difficulty into the already bad day.
Absolutely correct, in my considered opinion.
Far too may folks seem to 'rely' on TCAS as though it were infallable...sadly, sometimes it is not.
TCAS is simply another tool in the safety toolbox.