Well, this is a fun thought experiment at least. Perhaps Roger will take up the mantle and run some trials. After all, he's the guy with enough nerve to run a canster burst test :-)
I admit I've never not been able to find stove fuel in a pinch. It's possible the only risk burning alcohol is a gummed up stove (but, see below). Performance-wise, with alcohol's significantly lower energy density compared to white gas I'd expect less heat output. There's also the potential for some nasty vapors resulting from incomplete combustion--I'd stay upwind.
"Rubbing alcohol" concentrations range from about 70% to nearly 100%, the balance being primarily water. I'm guessing 70% would run very poorly indeed--perhaps not at all--in a pressurized liquid-fuel stove like a Whisperlite. The near-100% stuff should perform better. Would changing to the kerosene jet make a difference? I also wonder what alcohol's vaporization characteristics are compared to other fuels? i.e., what occurs as it travels through the vaporization tube?
My other safety concern is whether alcohol would degrade the rubber bits. Only MSR knows whether their seals and o-rings are alcohol-tolerant or not. I do know automobiles designed to burn E90 have fuel systems fashioned from alcohol-resistant materials.
As to the vast world of alcohol stove fuel alternatives, I'll guess we have a hundred-fifty threads on just that topic.