Honestly, the whole interview spiel delineating why he'll hold out for something better, seemed to be to be exactly like that "really sharp dug-in response" that is like an exacerbated J preference; TiNe to the core at least insofar as my understanding of it. Seems like he Ti'd to come up with his reasoning, and then let loose with Ne to hit them like a battering ram, kind of like the initial Harvard bar scene with the ski trip douche; he seemed more like an ISTx than Will to me. I think his childhood = Will not being able to be classified as "classic" anything, IMHO.
As for his rote memorizing, what if he is just a very bored, underwhelmed INTP that lacks the motivation to become a productive part of society, at least regarding his potential? Would a Sensor do those math proofs just for the hell of it? His childhood abuse would suggest that as at least a possibility. Also, isn't P-ness known for scrutiny of details? I used to be a champion speller as a child, and two things are certain: I am not a sensor, and my talent was based on a nearly eidetic memory and an affinity for reading quite a lot (including a good amount of meant for adults text) while withdrawing from the rest of the world around me, and definitely not an advanced understanding of etymology or the rules of the English language.