On page 14 of 5150 Star Army - Citizen Soldier, the 4th bullet says "If contacted by an Active Leader, it will turn into Duck Back status. This can be any active leader, section leader, platoon leader, leader of another squad, OR temporary leader. The only requirement is for the leader to be active.
So, if your only squad leader hunkers down, whichever figure steps up to lead the squad (page 11) can when active attempt to rally the a hunkered down squad leader. At least that's my interpretation.
This is a little different from Nuts where where there is a rally from duck back test where there is a chance a hunkered down figure will stay hunkered down .
Amado mio, love me forever and let forever begin tonight.