I mean, Jod isn't a Jedi, he's just a pirate. We already know that not all criminals are bloody-minded murderers, they just do what they have to do to survive. Remember Han shooting Greedo? Hell, even Hondo had a few soft spots for people he liked, like those Jedi kids.
And judging by that behind-the-scenes pic I've seen, I don't think Jod's trainer was a Master; she seems to be wearing a Padawan braid. Probably an older Padawan who escaped Order 66 and found a Force-sensitive kid before the Inquisitors tracked her down.
. . . which is exactly what happened with Kanan and Ezra --maybe Jod is what Ezra could've turned into if everything had gone wrong.