Let's not ascribe these social issues to one or a single type.. I've met many types with these issues, including people I think might be INTj, ISTp, ISTj, ENTp, and maybe even a few ethical types. I cannot be sufficiently certain of their types, but I can be certain that not all of them were ILI. The probability that everyone I've ever known who have expressed these issues to me being ILI is so small as to have no weight in my mind.
Some socionists relate

with emotion as the latin word that is used to encapsulate the concept is

. Some people will say that it deals with more then emotion and I will say that it does as well, but emotion is certainly one of the primary focuses of

and not social fluidity. Emotion althrough a component of social interaction is not a requirement, often weak

people can deal with social interaction thru more business like behavior.
I do not know Niffweed, so I do not know if his social awkwardness has to do with

PoLR but social awkwardness and inexperience is most definately not equal to

PoLR. I've met some very socially fluid and engaging INTp's in my life as well.