I wonder if the devas/humans who have niyata micca ditthi are dvihetuka(since it lacks the amoha root), and maybe that is why they could be afraid of Nibbana. To be clear, I’m not saying that anyone who is afraid of Nibbana is dvihetuka, perhaps more along the lines of a tihetuka who didn’t remove all the 10 micca ditthi just yet. I myself in the past, would probably not have regarded Nibbana as that great, but now I see this as the highest goal.
On a related note, when someone removes the 10 micca ditthi, it is said they have entered the mundane Path and are getting closer to grasping tilakkhana. I’d think this would not apply for those with dvihetuka as they wouldn’t be able to in this bhava. So then is it even possible for a dvihetuka person to remove all of the 10 micca ditthi within the same bhava?