I left it out because it's completely irrelevant to the argument. Taking a set of examples and trying to determine the rule from them is inductive reasoning and can never prove the rule. Add to that the statement that Auram spells usually deal with a phenomenon, and you should specifically expect most examples you find to be about phenomena. So that statement essentially says that you if you look at a bunch of example spells, you will probably only find phenomena even though that is not a restriction on Auram - in essence pointing out that using just a few examples to determine the rule is faulty.
Why only look at MuAu? Why not look at other Auram examples? How about Perdo Auram? Is Room of Stale Air not a valid core spell because it targets the air as opposed to a phenomenon? It doesn't make a breeze stuffy and uncomfortable, nor rain, nor the other targets in the MuAu spells, just the regular air as a gas. Noting that there actually is an example of a core book spell that treats air as a gas while there are many more examples that treat air as a phenomenon, we can see exactly what I stated above about using just a few examples.
To make the assumption you must trash the very sentences that tell you to use the things you're referencing, so I don't consider that a vaguely reasonable stance at all, let alone the most reasonable.
Targeting a Part of the air is just like targeting a Part of the ground. This is exactly what allows you to work with parts of the ground. The normal description works, so it "can, of course, be used."
Yes, I should submit that. I have a few more elsewhere, too. Speaking of errata, your analysis of the MoH errata.. I have submitted over half the items in the errata, and that includes nearly every one of the items for MoH. None of mine for MoH and, as far as I can spot, none of the others has anything to do with violating a guideline. They're nearly all miscalculations or misquotes. I'm not saying you're wrong about some being questionable, but citing the errata to back you up on this seems questionable, too. Can you tell me which questionable use of a guideline in MoH was removed in the errata?