I think if you look at the constitution it becomes clear that the Baha’i are excluded from protection by the constitution. The language used perhaps indicates what the source of that is in terms of giving Shia Islam a privileged status and tolerating Sunni Muslims.
The logic for giving this protection to the other, the ahl al-kitab, the Jewish communities, the Christians, and the Zoroastrians, therefore leaves out others. It would appear that's because the Baha’i are not regarded as people of the book, and that's why they're excluded. I have not heard this spoken publicly, but there's a claim that they are a cult, a claim that they are not a proper faith, speaking of the fact that there is a problem with the Islamic creed's response to the Baha’i faith. So it is very much a religious-based objection to the Baha’i faith that underlies their policies towards the Baha’i.