Combine labneh, lemon zest and juice, salt, pepper, garlic, and oil in a microwave-safe bowl. Set aside.
Cook pasta as package directs.
Meanwhile, pulverize saffron with a mortar and pestle. Add 1/2 cup hot pasta water and loosen saffron bits. Pour into a small saucepan, add butter, and heat until simmering; keep hot. Microwave labneh-lemon mixture until hot but not boiling, 1 minute. Rinse crab with hot water in a strainer to warm.
Drain pasta and return to pot. Toss with saffron butter. Add labneh mixture, crab, half of dill, and a little Aleppo pepper and toss very loosely to mix slightly. Pour into a warm rimmed bowl. Sprinkle with remaining dill and a little more Aleppo pepper. Serve with more Aleppo pepper at the table.
*Find labneh at Middle Eastern markets, Aleppo pepper in some stores' spice aisles, and Aleppo and Urfa biber at worldspice.com