Depends on the definition of "breaking up." If it means some small part came off, not enough to cause "immediate disintigration," but enough to start a chain of events, then I have the impression NASA is open to that theory. Their instrument readings, etc. were not "typical" at that point, and they are hungry for an explanation.
If "breaking up" means breaking the shuttle into two or three big pieces, etc, then I think all will agree that event happened over TX.
It is unlikely that the Astronauts were able to talk calmly after the shuttle came apart.