Fake Block (shulker + falling_block combination) with Motion tag set is only solid from 5 sides

If I have any NoAI, Invisible shulker with the Motion tag set to, e.g. [0.0d,0.0d,0.02d], you can walk on it OK, it stops you from going through it on the sides, back, and bottom, but from the front side, it is not solid, and the entity's hitbox is the only resistance. You can easily push through it, but ONLY from the front.

A video showing that the front side allows a player to move through a shulker when moving is attached.