It is currently not possible to end camera rotation (hold LMB, move mouse around to rotate camera) from addon code, as CameraOrSelectOrMoveStop() is protected. The equivalent for terminating mouselook (hold RMB, move mouse around to rotate character) is MouselookStop(), which is not protected.
It would be nice to have an unprotected function like CameraStop() that would terminate camera rotation, as if the player had released the left mouse button.
[I could also live with CameraOrSelectOrMoveStop being added to the restricted environment, but that seems like the wrong solution for this issue -- the camera functionality should probably not be protected in the first place.]
... and you do get used to it, after a while.