Regarding armor timing for squad leaders, from the manual:
"Squad Leader: Gets 1 armor while patrolling and must be dealt with first."
"Note: the Squad Leader's armor refreshes each turn."
From this, I understood that at the start of each opponent's turn, the Squad Leader is given 1 point of armor which is lost if it gets sidelined. Seems straightforward until Grappling Hook is taken into consideration, because if a patroller gets moved from Squad Leader to another slot, it is still patrolling, even though it is no longer a Squad Leader.
So, there are 2 ways I can interpret the rules.
1) At the start of each opponent's turn, the Squad Leader is given a point of armor which lasts until end of turn or until it leaves the patrol zone, in which case getting moved from Squad Leader to a different slot does not remove the armor, and getting moved into the Squad Leader slot does not grant a point of armor.
2) As soon as a patroller enters the Squad Leader slot, it immediately gains a point of armor, and that at the start of each opponent's turn, it is repaired if it was destroyed on the previous turn. This would mean that getting moved out of the Squad Leader slot would immediately remove the armor, and getting moved into Squad Leader slot would immediately grant it. A consequence of this would be that in exceedingly rare cases, an opponent might need to chew through Squad Leader armor more than once in the same turn.
My feeling is that (2) is the intended behavior, but I can see RAW arguments to support either interpretation.