I'd more trust the spiked results and find the overall results suspect.
Speculation:
With known perfectionism, I wonder if he answered the tester with frequent "I don't knows" which internally translated to "I'm only 98.32% confident in my answer."
IQ tests require a certain number of failures to discontinue a section, which is a nasty trap if someone tends to clam up once their confidence is undermined.
When my eight year gets into that kind of mindset, I have to ask very soft, open-ended probing questions. Like, "are you familiar with different meanings for the word 'contains'" vs. "What is the meaning of 'contains'?"
Obviously, I don't know if that is what you are facing.
