Yes, there is no measurable evidence for N or S; because the brain is more complex, but there is empirical experience of these phenomona when considering the activities and cognitive reasoning of many individuals - sure analytical psychology is not an absolute fit to the brian, but that's okay. That's as empirical as it possible within a reasonable and acceptable margin of error. I don't need to 'touch' N or S or T or F to see and gauge their effects.
Its seems simple to me; there are empirical cognitive modes which people relate to. That is all that is neccessary. Sure, you can't track them back to neurons, but people do behave along cognitive style modes.
And yes, it's quite appropriate to think and expand into this depth because it opens us up to avenues that might help us to find better ways to evolve and manage these systems.
I respect your right to a different opinion; I just can't agree with what you have said when relating it to my own experience and understanding. I think this is my Te clashing with your Ti and how I'm happy to see the demarcation and accept the margin of error where you see an unacceptable error to approve of the system.