Soak eight 8-inch wooden skewers in cold water for at least 15 minutes and up to 1 hour. Meanwhile, make the mojo: Combine the orange juice, 1/4 cup olive oil, the pickled habaneros, half of the garlic, the cilantro, mustard, and salt and pepper to taste in a medium bowl; whisk well and set aside.
Combine the remaining garlic and 1/4 cup olive oil in a small bowl. Preheat a grill or grill pan over medium-high heat. Skewer the shrimp and brush with some of the oil-garlic mixture on both sides; season with salt and pepper. Grill until opaque, about 2 minutes per side, brushing with the remaining oil-garlic mixture. Arrange on a platter and drizzle with the orange-habanero mojo.