(GAMEPLAY) Graves is still able to dash using his ultimate while bound.

I was in game as lux and bound the enemy graves under turret, but he easily ulted out of turret range and killed me. My complaint isnt that he is able to ult while bound, i just find it confusing that he can still move his character while bound in place. i think this falls under the definition of bug. If damaging abilities that move the caster still work, why cant caitlyn e while bound? this only happend to me once but i believe it is an unintentional bug