Good points. INFJs can be very private with who they really are. Seems to me that INFJs have ideas upon ideas swirling in their heads but find it difficult to verbalize sometimes what Ni is cooking up. I think INFJs tire and grow uncomfortable if they have to explain who they are to others. What works with ENxPs is exactly what you said. We have a knack for sizing up people with relative accuracy and 'get' them without having to be owed a deep exposure of their 'inner self.' A base understanding might quickly be formulated from the get-go which makes growing a relationship easier. It's nice to start a project with the right tools instead of the wrong ones.Entps have a high tolerance for and interest in complex problems and if it's important to them, have the skills to allow the infj to feel understood and get them to verbalize their thoughts and feelings more easily as well as draw them out of themselves. They also are good at getting them to try new things that they wouldn't on their own and infjs appreciate someone who is able to do that.
Entps can quickly read people and get a grasp of what it is that motivates them. They also not just tolerate, but enjoy solving problems in the relationship and can be very creative with finding ways to develop new layers of meaning in the relationship. I think that with infjs, there is less pressure to always be "on", than there is around other people, partly because the entp has more to engage with, and because the infj wants to get to know more sides to them and shows an interest in that part of them rather than just the caricature version of them.
I think ENTPs do the stabilizing for INFJs in this relationship actually.Infjs I think serve as a bit of a stabilizing force. Their Ni makes a nice counterpoint to the entp's ne and they see things in a novel way, which entps appreciate. They often can reach similar outcomes but get their in completely different ways, which both find interesting to investigate. I think infjs serve as a good sounding board for entps, which they often don't have, and allow for them to explore ideas and feelings in a way that rarely happens with others. I appreciate both cleverness and a bit of bluntness (not possessing either quality in the way they do), and I think entps like having someone recognize their strengths beyond solely their value as entertainers.