Well Iune's weapon Sigh also pushes him. But Lycus's shield's function is not to stop CC (crowd control), the function is to stop DAMAGE. If I had a shield in front of me and a man was hitting it with a baseball bat I would not suffer damage, but I would be affected by the impact in that the blows to the shield would hinder my movement.
Lycus's shield protects him from damage, but pushing on his shield pushes him. This isn't a bad thing as Lycus needs to have SOME counters in the game.
BUT I will say that Tolchok may need a slight damage nerf again to justify it's utility. You can't have both good damage AND CC. Iune, however, is fine.