I think it's junk science.
They should still be allowed to air the AD though. All ads are lies of half-truths. Nonetheless, the airwaves are public and are supposed to be licensed to companies who will operated them in a fair and equitable manner.
It's not exactly like the New York Times being able to accept and reject ads, because unlike the paper which they buy themselves ... the airwaves are ours.
At least in theory.
Well, CBS rejects a lot of things for no good reason. PETA isn't receiving special 'mistreatment.'
The paranoid rumor mill likes to say that the money grubbing ranchers like to shot up feeder cattle with diethylstibestrol, a feminine steroid in order to fatten and soften them up. So therefore if you eat meat you have abnormal female hormones in your system that causes all kinds of health problems in women and men. Pure poppycock, but the vegans like to believe it.