What do you think is going on with the grades? Is he actually struggling with the material, or are there executive function issues with meeting deadlines, or personality conflicts with teachers, or…? The combination of uneven grades with very high standardized test scores will only accentuate the question, in the minds of AO’s, as to why his grades don’t match his scores. But the reason(s) behind the uneven grades may be more important than the grades themselves, which as you note won’t shut him out of all decent programs.
Iowa State could be another to look at - strong in aero, and not hard to get into… but rigorous, so attrition is an issue, and he would have to be disciplined to do well. Rose-Hulman could be another to look at. Also U of North Dakota, particularly if he’s interested in aviation. (Is he more “aero” or more “space”…?)
(ETA, a little redundant now that AustenNut has posed some of the same questions, but I’ll leave it…)