You asked "why this would make a good self defense round", I replied "in general..." as to why they are recommended.
Short barrels often have difficulty getting a bullet fast enough to do both expand and penetrate to recommended levels, especially if the cartridge isn't designed for the barrel length. Hence the recommendation for wadcutters/semi-wadcutters in those circumstances. If you've got a cartridge that both penetrates sufficiently and expands (and has tolerable recoil and shoots point of aim) then that's the better option. Wadcutters are for when that's not true.