Boy, talk about semantics! Or is it the old blind men and the elephant?
The AIM is one of a number of FAA "guidance documents." They are "non-regulatory" but all that really means is they have not gone through the hoops required to have the legal force of a regulation. Instead they sometimes have some "sort of" regulatory effect. They sometimes reflect what the regulations say in easier language. They sometimes expand on what the regulations say. They sometimes give us insight to what the FAA says the regulations mean. They sometimes even have quasi-regulatory force because a regulation tells you to look at them (look at the FAR 1.1 definition of "suitable RNAV system"). And they sometimes just provide helpful information that have no regulatory impact at all.
I think the AIM really says it best when it describes itself as the "Official Guide to Basic Flight Information and ATC Procedures."