It's a balance of factors. When I am riding along a ship, and the pilots asks for a back, I want the direction of the pull to be as straight back as possible.
Since that ship is so high, putting it in the bullnose would put the weight of the pull on the top inside of the nose, creating a pull that is down-and-then-back.
I could alleviate that by letting out more ship line through the nose, but I've got a 55 year old deckhand. I don't want to make him haul in 150' of nine inch line by hand.
Also, running the line straight back to the port side of the H-bit tends to keep the bow of the tug pinched in while getting dragged along (imagine someone pulling a line tied around your left armpit). I do that when I'm feeling lazy and don't want to fuck with the rudder for the ride.
There are all sorts of ways to manipulate the makeup on the H bitts and buttons to counteract wind and current when working a ship. Those tractor tugs have it easy.