Obviously this is a quick sketch and things would have had to been figured out logistically. The dock could have been placed anywhere. There's easily a way to separate passenger boat traffic and fireworks traffic. Obviously there would have been separation established.And the dock that you have on the map is right where all the fireworks are stored.
So whenever they were loading the barges for Illuminations each night, all boats would have had to stop running, even if it was deemed safe to transport large numbers of people through the storage depot at other times.
I doubt Disney would have let that hinder this plan.