If one was absurdly introverted, I don't see why it's not a possibility it could be one's dominant mode of cognition throughout life.
Noted.
If that's the only place it comes from (which I'm not sure it is), then that's a reasonable explanation.
It still doesn't discount the possibility that he's a type other than INTP, though.
In fact, that argument serves to discount in determining his type any time he mentions what functions he uses, including in the Freeman interview.
And, frankly, no one has come close to dealing with what I originally brought up in this post:
http://www.typologycentral.com/forums/showthread.php?t=50838&p=1685476&viewfull=1#post1685476
All of the arguments since have essentially been footnotes to what I wrote in that post.
And much of what I cover there hasn't even been dealt with/touched upon.