Odd Sort of Security Rule?

American Airlines tells us — and my sense is that this is the general TSA policy — that

All liquid and gel items must be placed in checked baggage only....

Exception: Baby formula or breast milk if a baby or small child is traveling; prescription medicine with a name that matches the passenger's ticket; and insulin and essential other non-prescription medicines.

I must be missing something here: Seems to me that a terrorist who wants to smuggle aboard explosives precursors just needs to fake a prescription label, no? Or if that's somehow too hard (I can't imagine how it can be), he can fake some symptoms, get a prescription for a liquid or gel medicine (granted, that might involve a day's delay), empty it out and refill it with the bad stuff.

Or is it that the prescription-bottles-only rule will diminish the number of bottles to be checked, and TSA will actually check each one to make sure that it's not filled with explosive precursors? That's the one sensible explanation I can see for the "no liquids and gels, but prescription bottles are OK" rule — but is TSA really geared up to perform this sort of checking?

Incidentally, I can see the prescription-bottles-only rule working for a few hours, if it's not announced — that way, if terrorists are then trying to execute a plan, they might be foiled because they hadn't anticipated the need to use a prescription bottle. But once we're talking about plans that are even a few days or perhaps even several hours away, and the prescription-bottles-only policy is announced, the terrorists can easily adapt themselves to that change, it seems to me. What am I missing here?

UPDATE: Some commenters suggest that it would take some pretty large bottles to make enough explosives to bring down a plane. My understanding from press accounts is that it only takes a little of the right kind of explosive, and a prescription bottle or two of cough syrup could fit what's needed. But if that's not so, or if the TSA is actually closely examining all the many prescription bottles that it's likely to run across, then the policy may make more sense than I thought — though I'd still wonder about the breast milk / baby formula exception (necessary as it is), plus also the ability to smuggle liquids and gels in various other ways (not hard in body cavities, I'd guess, though again that depends on how much you need).

FURTHER UPDATE: Perhaps the breast milk / baby formula exception might work because it's limited to people traveling with small children; I expect that even some would-be suicide bombers wouldn't find it easy to find babies whom they could enlist in their suicide squads. As to one commenter's note that mothers are being asked to taste their children's milk, I can say that Thursday morning we flew with a bottle of milk in our carry-on, and no-one said a word; maybe they just didn't notice it, or maybe they didn't have a tasting requirement to enforce.