It certainly makes for an interesting news item, especially to readers of this particular R-I forum, but I don't know how poor put-upon NAB would get exactly what it wants here... How would they plan to enforce this without using our tax dollars to hire another two thousand FCC agents to patrol every college campus, jogging path, and truckstop in the country in search of devices that throw (heavens!) 500 uV/m instead of 250 at 10 feet?
For that matter, wouldn't a device have to be pretty egregiously overpowered to cause any significant interference at all? Let's go, say, 40 miles out from a major city, where the market's C-FM's are still throwing about 65 dBu... Even a device with ten times the legal Part 15 power would only throw a given signal strength 3.2 (root-10) times as far as a legal Part 15, meaning its 48 dBu (250 uV) would go out for around 32 feet, and its 63 dBu (enough to trip the receiver capture against the other signal) for probably around twelve. Being in the other lane on a freeway puts you almost twelve feet from the guy you're passing anyway... And this is all assuming the device's operator has chosen to tune it right ONTO a locally occupied frequency.
For the sake of argument, let's take a device that's ONE HUNDRED times the legal Part 15 power, and say we're in the middle of nowhere, trying to get a 50 dBu country station from Sheepsbutt, the nearest burg of any consequence. 100 times Part 15 power is 10 times Part 15 distance, and a 48 dBu here would trip the receiver capture... but the 48 dBu signal is still going only 100 feet. If you're passing a semi at 5 mph over his speed (7 feet per second), you're still only missing fourteen seconds of the story about Kenny Chesney's sexy tractor... and being that we're in the middle of nowhere, there are dozens of other open frequencies that modulator could be on, anyway! (I can speak at least for myself in saying I prefer the most open frequency possible, since even if I'm 7 dB stronger than the theoretical incoming signal, I can still hear that ANNOYING signal-mixing squeeeeeeek under my audio...)
With all that in mind, the NAB's modulator obsession just looks like so much sour grapes over the influx of new audio technologies and services. Sorry guys, but if you wanted to keep your listeners, maybe you could have ditched the arrogant insistence on sticking to your hackneyed, "don't surprise the listener" format science, told your CHRs to cut out their 90-minute turnaround time on currents, and chosen to value service quality over corporate consolidation and penny-pinching.