iPad Air aluminum scuffed badly. Should I worry about it? My 2 year old son managed to scuff the back of my iPad Air by pushing it on its back across a ceramic tile floor.  The worst of it is near the top by the mic.  Are these scratches merely cosmetic, or do I need to worry about the aluminum oxidizing?
I wouldn't worry - looks like you got off without a scratched lens cover and only light cosmetic damage.

In general, Aluminum oxidation is a good thing as it seals the metal and protects. However, despite not being able to pin down the exact alloy that Apple uses, I know from experience that the iPad cases are not prone to oxidation even when deeply scratched or gouged.

I have never seen an iPad with structural or even cosmetic issues due to corrosion due to the anodized coating being scuffed. I have seen many iPads used in a marine environment and saltwater spray and/or the highly saturated air usually kills the circuitry inside far before the case can wear or corrode.

I'd say, clean up any sharp scrapes or cover them with a case and don't worry about the effects of the scratches.