In a small bowl, whisk the EVOO, vinegar, garlic and thyme; season with salt and pepper.
Preheat a grill to medium-high. On a large rimmed pan or plate, arrange the pork chops, peaches, bell pepper and onion. Drizzle with 2-1/2 tbsp. of the dressing and turn to coat; season with salt and pepper. Grill, turning occasionally, until the pork is browned and cooked through and the peaches and vegetables are tender and charred in spots, about 6 minutes. Transfer the pork to a cutting board and let rest.
Toss the arugula with the remaining dressing and divide among 4 plates. Thinly slice the pork, then arrange with the peaches and vegetables atop the arugula.