I don't think you could tow 2300lbs from the bumper, or at least I wouldn't even want to try it on newer vehicles.
Another possibility as well is that it may depend on which suspension package was ordered with the truck. If you get the base model truck it has a very light duty suspension so I'm guessing that would be the reason for the smaller rating. I know with the 93 ranger my grandfather had, the rear of the truck actually sat higher because it had the heavy spring package on it and had a higher towing capacity than the same ranger with the standard springs.
Another thing too, your info states the "sport" model, that's your problem, it has the sport suspension on it, its tuned for a sporty ride rather than for cargo/towing capacity. They have different springs/shocks for the sport models so they will not carry as much weight as say the standard base model, or the upgraded models.