I got in an argument and I was defending one of the theories about Venus' slow prograde rotation. I'm defending the theory which states that atmospheric friction, over a period of billions of years slowed initially fast rotation of Venus and made it go prograde. My opponent says that it would only be possible as a result of collision with a body three times larger than the moon in early Solar System formation. My point is that such a collision could disintegrate both of the bodies and after all the matter condense it would be subjected to tidal forces of the sun (due to its proximity) and orbital energy cause the protoplanet to start rotating counterclockwise. Please help me with that.