Ni is quite stubborn on its fixed set of ideas. (Although Ne types are usually the only types that can break through the ice of the Ni, maybe you meant you are a Ni-user open to the ideas of Ne-users?). This is just general info, nothing personal, i dont know you.
About the general thread here:
The repetitive aspect of aspergers/autism is a clear Ti sign. And the long fixation on it shows a weak perception function. They could be INTPs which are far more Ti (and less Ne) than the average INTP.
Another (unconventional) theory I have is that they could actually be a Ti/Te mix (unmapped terrain in MBTI). In that way their Ti mix with their Te (as functions dont exist, they are just navigation points on a spectrum), creating their own world, by just deciding/judging/taking-action. Thus not using a perception function much. (Perception would still be there, but much weaker, lower priority, like function 3-8).
If function mixes may exist in this "new model" anyway, then their low/weak perception should logically be an Ne/Ni mix or Se/Si mix. As the entire jungian function geometry should be looked at from a 45 degrees perspective in this model. (This might generate Ne/Ni confusion in the MBTI model, if this model is true)
Low-functioning autism (e.g. not the aspergers) could be a Fe/Fi mix. This is the "moron" archetype, which is a actually very common type if you research human history. Imagine this to get the picture: The moron will be the good over-helpful Fe as well as the raging demonic Fi, in one person. The moron is your best friend (Fe) or your worst enemy (Fi), all in one person, and is totally externalizing its control to an external controller (as unlogical/F as you can get). They are simply blind goons, because their perception function is weak, its all judgement. (blind=strong judgement, weak perception). They seem "stupid" because of their weak perception, but once its in them, they can act upon it. The trick is to get it in them (through their weak perception).
For me the Ti/Te and Fe/Fi is extra plausible because the shadow theory holds.
They would be each others shadow (the high functioning Te/Ti autist and the low functioning Fe/Fi autist), and since shadows are hard to seperate for the casual/quick observer, it explains why it is all clustered into the big "autism" package by those casual/unknowing observers, known as psychologists-that-havent-heard-of-typology (and for sure not an advanced thing such as shadow theory). Especially in young children it is hard to see the underlying intent of the double-sided shadow effect of their actions. As the fruits of their labor evolve you can trace their intent, but before that its quite hard.