"coolant loss-protection system" question

I just bought a 2001 Impala with the 3.4L engine. Reading about the car, I found that it has a "coolant loss-protection system". From what I've read, when the engine overheats, cylinders are disabled and the "reduced engine power" light comes on. When this happens, you can SAFELY(!?!?) drive another 50 miles. I can't find anything about the system in Identifix, I'll check ShopKey at work on Monday, but they've never had any information that Identifix doesn't. So I'm asking here.

My question is, how exactly does the system prevent engine damage? No traditional overheat protection system lets you drive anywhere near 50 miles. The only thing that seems like it would give you that kind of range is to cut the spark alternating across all the cylinders and let the unburnt fuel cool the cylinder. But I can't imagine that the U.S. EPA or any European countries' equivalent would allow that.

Thanks,
Jason