Very steep nose attitude, not at all ‘flat’ so it should be recoverable. I wonder why not?
Though the pitch attitude is very steep, the inertia in the rotation may have been too great for the recovery controls (if fully applied) to overcome. The Seminole is essentially a twin engined Arrow 3, and the Arrow 3 would have demonstrated spin recovery for certification. But the added mass of two engines away from the center of mass of the airplane, (and fuel tanks further outboard?) could be more than control could overcome. And that assumes that the pilot promptly and correctly applied spin recovery control inputs. It is not common for pilots to briskly move and hold the control wheel fully forward, but that's what some types will require to break the stall and spin.