Okay, look (and I was coming back to post this thought anyway):
You cannot discern the difference between an Ni personality and a person who has had a real spiritual experience where something that normally is intuitive is NOT intuitive to them but a real, tangible, breathing FACT.
IOW, Donnie has "special knowledge" that most human beings do not have. What you attribute to Ni vision is actually a sensory experience for him. He's responding to that very real perceptive experience, with as much certainty as an S would responsible to a concrete experience because for him it was not an intuition but it is right in front of him, he has been given the knowledge as truth.
That's why the rules here are broken.
Even INFJs can't claim to have had miraculous experiences. They are operating directly from Ni. Donnie is operating from divine revelation that has also been shown to the audience, so we know the actual experience he gets his information from.
I mean, geez, I've had 1-3 serious spiritual experiences to me are equivalent of "fact" in terms of what I experienced, so I speak of those experiences as facts.. but it doesn't mean I'm using Ni even if I speak with 100% conviction over what I experienced and others would read it as intuition.
Everything else about him in terms of how he interacts with real life is very P. He flexes and adjusts to situations.