Add butter to pan. Once melted, add corn, onion, poblano pepper, and garlic; cook until onion is translucent and mixture is fragrant, 4 to 5 minutes. Add orzo and remaining 1/2 tsp. salt and black pepper; cook 1 minute; stirring often. Add broth, coconut milk, and fresh thyme; simmer, stirring occasionally, until the orzo is al dente and most of the liquid is absorbed, 10 to 12 minutes or according to package instructions. Add shrimp back to pan and garnish with basil.