The hubs on the S4 (pre-Brembo brakes) are identical to the SE hubs, except for the 58mm spigot. The hub is not a Toyota part....
I think this is "mostly" correct. However, I'm under the impression that the hub is identical to the Supra's in many respects, but rather than having 4 studs for the Mk2 Supra wheels, the face of the hub is drilled to receive the 5 bolts of the Esprit. The back of hub, for instance, where the rotor attaches, I think is identical, as obviously, is the rotor itself.
FWIW, I think it's just coincidence that the front and rear were both 60mm at the time. Toyota (front) and Renault (rear) were both using 60mm in contemporary designs. That makes me think the theory about keeping people from switching wheels may be on target. Sometimes, manufacturers will use different hub bores front and rear to prevent this. My guess is that Lotus didn't mean to have them the same by design...it just worked out that way because Lotus' suppliers used the same hub bore. Just guessing, but makes sense.