I found this to be an interesting discussion. I think there are a few things going on in Ren's analysis and in the general typology community about understanding Te and the relationship between Te and Fe that makes seeing the Te in Nietzsche difficult.
First, things that are contrary are not oppositional. Contrary things exist as two sides to one whole while opposite things are different ends of a spectrum that aren't reconcilable along the same axis of consideration. Fi is not actually opposed to Fe as they both make up what is feeling; Fi is actually opposed to Ti, because they are both introverted judging functions making different considerations. For instance, take a Fi dominate philosopher like Soren Kierkegaard. His philosophy with the leap of faith, the dichotomy between reason and absurdity, or you either pursue faith or your either pursue reasoning, is a sort of absurd existential dichotomy, because his psyche's philosophical mission even though he is antagonistic towards Hegelianism is to oppose Ti. Again, Fe and Fi are counter valuing, but Fi and Ti are oppositional. Similarly, Te and Fe are oppositional, because they are both concerned with social realties, but Fe care about what the groups feels and Te about what the group thinks, so they move in opposite directions of consideration, hence they are opposites.
Now, both Te and Ti can be systematic, but Te is less so interested in systems than Ti since Te isn't tied to any particular way of thinking as it prefers to think in a breadth or multitude of ways since it's divergent rather than convergent in thought. Te is willing to present its thinking in any way rather than some particular way or single way as Te doesn't see a single path or way of doing something as truer than the other without knowing what you want to achieve or convey. Pragmaticism and Perspectivism are Te schools of thought as opposed to Rationalism and Absolutism which are Ti schools of thought.
Also, Nietzsche doesn't advocate you adopt his way of thinking, but to use his philosophy as a guide to free yourself, if you're the right kind of person, from the thinking of Christian and Egalitarian societies. Nietzsche is actually pointing out the contradictions and absurdities of thinking when reflected on social, moral, emotional, and psychological realties as these things were generally ignored and taken for granted in the history of western philosophy. I don't know what most people's reasons are for considering Nietzsche an INTJ, but I'm going to be frank that I think an INFJ might miss the Te in Nietzsche, because they're generally blind to Te, but Nietzsche is a Te user which is why his philosophy is in opposition to Fe realties. Where you don't see that kind of attitude in Dostoevsky even if he is fully aware of the paradoxes and contradictions of Fe and is quick to point them out.
Also, Nietzsche wrote in letters to friends, his personal diaries, and a few journals that thinkers like Kierkgaard and Emerson-(INFPS) were his existential counterparts whereas of Dostoevsky he felt he had things to learn from him as a psychologist and social thinker. Nietzsche felt that few were as psychologically perceptive and true philosophers of the mind as Dostoevsky, but he didn't hold Dostoevsky with the same reverence that he held Emerson and Kierkgaard as kindred spirits.