Earlier quoted context omitted.
Because a rifle isn't practical for close targets. A handgun is much better suited for that.
"A handgun is much better suited for that." I'll take "What is a carbine chambered in a pistol round for $200, Alex." The SUB-2000 uses the 9x19 round, so it's basically a pistol with better ergonomics. Defending a home with a full rifle round in close quarters, say a .30-06 or 8mm Mauser, would be kinda silly--but that carbine is fine.
Me, 1911 for retention, and maybe a long gun if I'm bunkering waiting for the police to arrive (slow to access in the main gun safe).