Unlike the person above, I think your argument holds up pretty well. It is possible that he could be an INFP with maybe a thinking enneagram (probably a 5). I still lean towards INTP though (possibly with a feeling enneagram!) because he is required to use his thinking function quite a bit and I don't see any use of Te, only Ti. Maybe, you should try thinking about what his enneagram might be and that might lead you to a more secure typing.

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Although, I am an INFP who has been compared to Reid .