Yeah I'm with Henz on this one. Maybe we'll find out more during TFU, but based on what we know so far, she seems like a coward for fleeing the temple and leaving the younglings defenseless against Vader.
Originally Posted by Wookieepedia
As the Jedi Temple's commander and defender, Shaak Ti was present during the fall of the Jedi Temple, during which Darth Vader himself set out to kill the Jedi Master. Knowing she would not be able to defeat Skywalker and the 501st Legion, she fled Coruscant and went into self-imposed exile on Felucia, where fellow Jedi Knights Aayla Secura and Bariss Offee were shot down. Some time later she met Jedi Maris Brood, who was bent on revenge against Vader. Shaak Ti convinced her to go into hiding on the planet Felucia, where she was training the Force sensitive natives for an eventual conflict with Vader and his secret apprentice.