Interesting. Why would Rigby want to offer a stalking rifle without even the option of iron sights? Save a bit of money? With the increased popularity of present return-to-zero quick detach rings I think retaining the option of iron sights, at least the front sight, makes more sense. I primarily hunt with optics but in bad weather or very rough/steep terrain I will remove the scope and switch to irons.
If economy is the objective, I would suggest tapping the receiver for traditional scope bases, plug them with blind screws, and include a ramped brass bead front sight minus hood. If the front sight ramp is high enough, a quick detach ghost ring rear sight can be attached to rear scope base as needed. Or a red dot sight (which would not require front sight).
30-06 will always be tops for a stalking rifle.