Read an interview with the showrunners, they wanted to do a bit of the Batch with some Jedi and the idea of letting a Padwan get away to establish things.

It was Filoni who suggested it be Kanan which makes sense and while a shift, not the first time it's happened (see the Ahsoka novel being different on her during Order 66 than Clone Wars) and was fun hearing Freddie Prinze Jr voice the role again.