Willa:
My impression, from reading through the manual, is that the IAS should be used as a catalyst for discussing the needs of the child and possible options. Not just totalling up the numbers and getting and a score, although that is the primary purpose. In Mite's case, I think (my interpretation) the authors intent for using the IAS would be to look at all the strengths, identify how his lower skill areas impact the achievement testing, consider how an IEP and appropriate accomodations would INCREASE that achievement and THEN decide about the grade skip.

But haven't they already decided to do the grade skip for Mite? If so, the score on the IAS should be irrelevant - since they already decided he is a good candidate for the acceleration.
The IAS is just intended to be used as a guide for making that decision - not a written in stone assessment. But, again, that's my humble interpretation of the IAS!