William's delivery is thinly glossed over in passivity; he's intent on drawing direct results/responses from whoever experiences his art with pre-defined questions, which is an alien process/concept to me.
There's a different sort of cockiness that the two types exude that seems to be tied to their assertiveness and desire for official beginnings/endings. Consider the statement, "infps tend not to be as active when analyzing situations, aka purely based on emotional resonance, which can lead to making decisions based on inconclusive evidence." That sound like you could've written it? Because at times I've certainly felt a strange sort of arrogance by what I think might be too heavy a reliance on tertiary Si. Who knows what to call it.
For instance, I wrote a childrens book for one of my last college courses that had a lot of dense as fuck emotion; as I read the thing in front of everyone, I carefully measured the temperature for subtleties, jaws slowly melting with each page. Once done, I left. Whether it's energy level or whatever one wants to call it is up to...
Maybe Williams has lots of infp friends/family that influence him, or maybe it's too subtle a difference that I'm able to put into words. We can probably agree on the idea that infjs are less apt than infps to let their feelings dictate their actions/projections due to their function order. Williams' active collection of information (including emotional responses) leads me to believe that he's not working primarily from a feelings-based function, but from something else. He doesn't jump to lazy conclusions like an infp.
I see this as Je at work; build it and they will come.