I know quite a few ILEs in person, actually, which is one reason why I'm so sure Lennon isn't one. ILEs can get excited and energetic, and their 2-d Fe makes them more emotional than, say, LIIs, who have 1-d Fe, but I wouldn't say that their primary view of the world is rooted in emotion and passion like John Lennon's clearly was. For all their excitability, ILEs are logical types who view the world in a logical way. The majority of their decisions and goals are made for logical reasons, not emotional ones. They're primarily driven by curiosity and a desire to explore and understand the world, not by passion and a desire to influence people emotionally.
I don't really understand how Fi-PoLR would create an inflexible all-or-nothing attitude. I've never encountered that view before. Could you explain, so that I can understand your reasoning?