I propose mobs being unnable to shoot or attack while in a boat.

I'm currently trying to complete the hardest advancement of them all: "How did we get here". I'm almost there, but there is something that is really anoyying me: the Shulker. The advancement objective is to have every single effect applied at the same time, including the levitation effect caused by the shulker. What I have done several times is transport the shulker to the Overworld via a boat, the problem is it keeps shooting when there isn't any block below the shulker. So I have failed to transport the mobs when entering an ocean (I'm transporting them near an ocean monument so that I also gain the mining fatigue effect) because they keep shooting and they don't even hit me, they hit themselves and die and it's really annoying because I'm so close to geting the advancement but they keep dying.

So my proposal: mobs being unnable to attack or shoot while inside a boat. This may seem as something unnecessary because then people may exploit boats, but people already exploit boats so I don't really see the problem.