OK, not a slam here, but as a point of discussion, why do you consider this "unethical"?
Would you consider the .45 Colt to be an "unethical" round for deer hunting? The design that evolved into the .45 ACP eventually settled in at about the .45 Schofield cartridge power, being the same caliber, same mass (the Schofiled had a 230 grain bullet loading), and a slightly higher velocity profile for the 230 bullet. It's generally slightly under the performance of the original .45 Colt, though only because the original .45 Colt was loaded with a 250/255 grain bullet at around 900 fps.
And the .45 Colt has a proven history as a hunting round when used in rifles. So why would the .45 ACP not likewise be acceptable?
And certainly the .45 ACP comes in a wide variety of bullet designs and loadings, many of which ought to provide significant capabilities with respect to taking down deer. If they can take down a human being from a pistol, I see no reason why they can't also do so coming from a rifle/carbine, which would impart a moderately higher velocity than from a pistol (especially if loaded accordingly).
Deer organs are not significantly more or less accessible than human organs when it comes to being shot.