Malzahar sheild vs Gang plank's barrel

Hello

i was playing a game against as and i realized that when i land a barrel all the damage is negated by the shield, naturally the slow won't apply but to think that a skill shot as hard to land as Gp's barrel would be completely negated by the shield that is passively acquired and has no mechanical manipulation is in my opinion a bit too much, now i am not a game developer. so my question: is this how it was intended to work and is their any possibility it might be looked at.

thank you and please take my opinion with a grain of salt.