Heat oil and garlic in a medium saucepan over medium heat, stirring occasionally, until garlic sizzles (do not let brown), about 1 minute. Add chili powder and cayenne. Cook, stirring constantly, 1 minute.
Add ketchup, bourbon, molasses, vinegar, sugar, mustard, and Worcestershire sauce. Simmer, stirring occasionally, until slightly thickened, 12 to 15 minutes. Season with salt and pepper.
Heat grill to medium-high. Season chops with salt and pepper. Grill, turning once, until a thermometer inserted in the thickest part (avoiding the bone) registers 135°F, 10 to 14 minutes, basting with glaze (about 2/3 cup) during the last 4 minutes of cooking. Transfer to a platter and baste again. Serve with remaining glaze.