The point is that the ship started giving warnings several minutes before the allision - and that was soon followed by emergency services communication that were amazingly successful at limiting the human loss by closing the bridge and whatnot.
The skiff is required by OSHA whenever work is being done “over or near water” as this bridge work would certainly be included. And one of the stated functions of the skiff is to remain in direct (“walkie talkie”) contact with the work crew for emergency communication.
The point here is that had the company had the required skiff on location in the river, it likely would have been aware of the ship, aware of the emergency communications, and could have given the work crew more time to escape. Of course I don’t think we know what they actually knew and when, so it is speculative. But that’s the point that’s being made - it was required by law, it serves an emergency communication function, being a vessel on the river would have made it particularly relevant in this incident . . . and the company didn’t have it.