Found this in the blanka section and this sort of explains why lariet is so boss. Had not seen this in this section yet thought it could be some help.
Orange: vulnerable from physical attacks
Blue: vulnerable from throws
Green: invulnerable from projectiles
Red Box: hit box
I think crouching lariet works because you are waiting till someone else is in your hit box before you hit lariet. So their attack never hits the venurable part of the lariet because it didnt appear till they were already in giefs lariets hitbox.