Here's the deal:
The designers didn't want to break up the JKR Jedi squad you'd use in other combat missions.
So why not use Shaak-Ti as the leader? Given her leader ability has no effect without Clones present, it wouldn't matter which of those two appear in the leader slot, and the decision was made to "showcase" KAM a bit more by putting him in that slot.
I asked why not place someone such as Aayla in the leader slot? The designer stated it would add another required unit (including the task of having to Relic up another unit you might not want to invest in) as a barrier to entry.
So, the decision to balance the mission around no leader ability was made and implemented.