It is true that compilation and minification are both code transformations (it's a correct reduction [1]), but this doesn't seem a very useful observation in this discussion. In the end, everything you do to something is an operation. But that's not very workable.
In practice, compilation is often (not always, agreed!) from a language A to a lower level language B such that the runtime for language A can't run language B or vice-versa, if language A has a runtime at all. Minification is always from language A to the same language A.
The implication is that in practice, deminification is not the same exercise as decompilation. You can even want to run a deminification phase after a decompilation phase, using two separate tools, because one tool will be good at translating back, and the other will be good at pretty printing.
