3.1 Action Segments An action segment consists of any one of the following:- A single unit or leader self-activating;
Based on 3.1 Action Segments, a single demoralized unit, of two or more in a hex, could self-activate, roll for recovery, fail and exit the assault hex without a parting shot since the other demoralized units did not activate this segment. Or a leader could activate and activate one demoralized unit of two, fail and exit the hex without a parting shot.
1.1 Summary of Concepts
Action Segments: In an action segment, a player can activate one unit, or a stack of units, or a leader and all units of his type (regular or tank) in his hex...
1.2 Definitions
Action Segment: The activation of a unit, leader, or stack of units, or a group of units and subordinate leaders under the direction of a single senior leader. Activated units may perform either fire or movement (morale recovery is a move action and assault is a fire action) (3.13).
14.3 Demoralization
A demoralized unit or leader:- Must attempt to recover morale (14.4) on its activation.
Based on 1.1, 1.2, 3.1 and 14.3 you can activate one unit at a time or a leader and one unit. Either way you are going to lose a step or two if your inactivated demoralized units are assaulted by the enemy before they can recover.