In a large nonstick skillet, heat the olive oil until shimmering. Season the chicken with salt and pepper, add it to the skillet and cook over high heat, stirring occasionally, until browned, about 8 minutes. Using a slotted spoon, transfer the chicken to a plate.
Add the orzo to the skillet and cook, stirring occasionally, until golden, about 3 minutes. Add the scallions, garlic and crushed red pepper and cook, stirring, for 30 seconds. Stir in the diced tomatoes, chicken stock, olives and peas, scraping up any browned bits from the bottom of the pan. Stir in the browned chicken along with any accumulated juices. Cover and simmer over moderately low heat until the broth is nearly absorbed and the orzo is al dente, about 15 minutes. Stir in the parsley and fluff with a fork. Spoon the pilaf into shallow bowls and serve at once.