Okay 4 things.
1. Thats not Zaheer. That guy in the picture is too tall to be Zaheer.
2. The reason that girl is focused on in the last episode is because she was featured two other times in the previous episodes. Once in the metal clan, and another time she was the front page story of the newspaper.
3. another reason she gets attention is because she has a celebrity voice actor (Zelda Williams) and is the korra equivalent of the gaurd voiced by Serena Williams in season 3 of TLA.
4. There is no chance in hell they would make the Captain of the Guard Zaherr's bastard child after what Henry Rollins said about Robin Williams.