Cook vermicelli according to package directions; drain, toss with 2 Tbsp. butter, and keep warm.
Rinse scallops, and pat dry with paper towels; sprinkle with kosher salt and pepper.
Melt 1 Tbsp. butter with 1 1/2 tsp. olive oil in a large skillet over medium-high heat; add 6 scallops, and cook 2 to 3 minutes on each side or until golden. Remove from skillet, cover loosely with aluminum foil, and keep warm. Repeat procedure with 1 Tbsp. butter and remaining 1 1/2 tsp. oil and 6 scallops.
Combine grapefruit juice and wine in a small saucepan; cook over medium-high heat 10 minutes or until mixture is reduced by half. Remove from heat; stir in remaining 1 Tbsp. butter. Divide vermicelli among 4 plates; top with scallops and sauce. Garnish, if desired.
For a golden crust, pat scallops dry before searing, and cook in a very hot pan, being careful not to crowd them.