Harkening back to an earlier point:
As for a safe harbor provision, there is no such thing in this regard. If the family stated wanting her on life support, but the physician went ahead and declared her dead so that the hospital had to remove care. Also if Texas has a law on the books stating that removing life support is illegal and the physician made a move to do so leading in death to the patient and fetus, then he is liable. The criteria is simply being established in that law, not being used to shield the physician. There is not much safe harbor in death.
Here, in pertinent part, is the safe harbor clause from the Texas statute you cited:
"§ 671.002. Limitation of Liability (a) A physician who determines death in accordance with Section 671.001(b) [i.e., the section that authorizes determination of death on the basis of irreversible cessation of spontaneous brain activity]... is not liable for civil damages or subject to criminal prosecution for the physician's.... actions or the actions of others based on the determination of death."
The language is fairly plain. Assuming the physician diligently followed ordinary medical standards for determining Ms. Munoz's brain death, how exactly could he or she be held liable, civilly or criminally, for declaring her dead, without abrogation section 671.002?
The safe harbor provisions aside, assuming you are correct that Texas law requires
the termination of life support following a declaration of brain death (even where the decedent is pregnant), how could a physician, who has merely declared a medical fact defined by statute, possibly be held legally responsible for consequences which the law then mandates? And, if termination of life support is not mandated in the case of a pregnant decedent, something more than the physician's declaration of death would be required before the plug could be pulled. In either case, I can't for the life of me see how a doctor would run any legal risk by merely doing his or her job and pronouncing the patient dead.
Kythia may be correct that the hospital's answer to the "to be or not to be" question turned on the availability of payment for the treatment it was giving to Ms. Munoz's brain dead body. It is difficult to imagine a clearer instance of gaming, however, than avoiding a declaration of death, which would otherwise be made in due course, so that the hospital could demand compensation for a course it chose on its own.