I think that they have an Sti with an option pack (OPC 92) that is equal with a Spec C with A/C.
The air-oil cooler was an option for the Spec C. I think it may be OPC94.
If we were to think for a minute that there was a package for an Sti, to get a VF36 and not be a Spec C, this is not that weird, because the complete car could still be an Sti.
It would have the non spec C suspension, have the full Sti weight components, no crank rear windows, etc.
Here we would love to get that stripped down, lightweight spec C, but if it was readily available, it would probably do like the base line Evo 8.
It was cheaper, but people did not prefer to buy it, by a large proportion.
So then you offer much like Chevy and others, option packages..
As far as what would the option pacage of the Sti do to the immobilizer? I have no clue, but my first reaction would be that it's probably immobilized. The only reason (under my opinion) to not have an immobilizer with the Spec C in V9 was to show a commitment to lightweight construction. A full weight Sti with a Spec C engine would go to a different customer, I would think.