Sorry, Slingblade, but despite 3B's troublesome methods of communication, he actually has a decent understanding of the process while you and many others do not. Here are some definitive sources.
The sentence in bold is what I think 3B is driving at in principle. Stated simply, if the FDA has regulations regarding certain terms, then if those terms are subsequently used in advertising (where the terms don't directly apply) the FTC will give strong consideration to those definitions. It does not mean that using the terms in an inconsistent manner is automatically misleading, but it does mean that it will be taken under consideration as to what the advertising is likely to be taken to mean. Thus there is a case to be argued.
Here's some more background, but it involves nutrient content. The principle is similar.
Once again, some key points:
* This is not a case brought by the FTC, but I'm reasonably confident that FTC policies, opinions and court rulings will come into play when deciding this case on the California statutes.
* I am only talking about the principles in the argument, not the argument itself. It's by no means automatic that Taco Bell will lose when the above is applied in their case. I'm just discussing how it should be looked at.
So, at this point I have presented two different official policy statements from the FTC showing that FDA regulations are considered when looking at advertisements. Anyone who continues to argue otherwise is just wrong. You can certainly how argue how much consideration should be given or whether the terms are actually being used, but the principle is sound.