To heedm, you said:
>>However, I still don't see how it explains the disk rising at the front. Does the disk rise at the front?<<
No, the disc does not rise at the front per se, in fact this is the reason I try to avoid comparing the pitch up to aft cyclic. The term “rotor disc” should never be thought of as a solid entity (sorry Lu), rather it should be thought of in terms of individual blades. The term is used purely for simplicity of description and ease of understanding. (I believe this was one of the points you were alluding to in your excellent description of gyroscopic precession.) Accordingly, when the rear blade no longer climbs as high in RBS as it did in the pre stall, there is no corresponding effect on the height of the front blade because the disc/tip path plane is not solid. The effect is that the tip path plane (again not a solid entity as such) is lowered at the rear without being heightened at the front. Hence the aircraft attempts to realign itself with the new tip path plane by pitching nose up.
Hope that helps. Please bear in mind that I am no aerodynamics expert, so I may be going off on a tangent.