UAL's SOP is irrelevant. In an emergency, FAA regulations give the PIC full authority to do anything [s]he deems necessary to ensure the safety of the flight:
§ 91.3 Responsibility and authority of the pilot in command.
(a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.
(b) In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.