Isn't the intent of 110.26 such that you shouldn't have to reach over an A/C unit in order to check voltage or pull out the disconnect ? Granted, the A/C units in Marc's photo make getting to the disconnect a bit snug but at least they are accessable without having to reach over the units for servicing. And granted, the A/C guys could have located the units a bit closer together to allow easier access (But then again, why should they be concerned, they're not the one's that will fail inspection ?). But, the fact is they're accessable.
Without the benefit of a photo from GENRT66 so we can only make assumptions that the AHJ was correct and locating the disconnect 4' above the A/C unit had some sort of accessability issue.