If nothing else the naval yard constructing the yacht should have known this could be a problem and planned accordingly. Like installing the masts last, downstream. Would probably be a PITA, but that's why Bezos is paying them the big bucks.
I'm not understanding why the masts can't be stepped on the other side of the bridge. You'd think they could simply hire a crane to do it. That's probably how they will do it at the shipyard anyways.
And why is the ship yard upriver of this bridge in the first place? Bad location.
context