Everything you say is correct. But the deviations shown in that diagram would only be guaranteed to settle in those positions, with those forces if there was no friction. With a krab the settling position would probably differ, as would the forces.
But you misunderstand the point of my post, which was to estimate the CHANGE in the tension of the top rope when the krab is pushed upwards and is retained in that position by friction.
The force does increase precisely because with the krab in the higher position the angles have changed.