After Moralo Eval, Cad Bane, and Rako Hardeen have escaped from prison, they steal a police speeder to get to the docks to steal a ship and leave Coruscant. Moralo Eval and Cad Bane take the front seats, leaving the back seat for Rako Hardeen:
Since this is a police speeder and the back seat is where criminals are detained, there are bars in the interior and on the canopy. Visually, this represents Kenobi's situation. His goal is to investigate a kidnapping threat against Chancellor Palpatine that Eval is allegedly involved with, and for the moment, he simply has to go along with Eval's plans in order to discover more information. In the same way that he experiences this temporary lack of agency, he's confined in the prisoner's seat of the police speeder.
