Maybe I do things wrong also, for I am with you. I tend to look at the 50% rule (NEC 2005 210.23), but that only applies to not fastened in place equipment. Based on 440.34 I feel their method is allowed though I do not do it that way. Sometimes I note that I do not do things the cheapest or the best.
I would be interested to know if someone else could show that the single circuit method were not allowed, but right now I don't see it.
P.S. Buffalo him by telling him that refrigeration equipment confuses the electrons in single circuits. The cold ones from the fan unit run into the hot ones from the compressor and they just end up bouncing back and forth with a period of 16.7 milliseconds (60 Hz), creating a changing magnetic field.