So we all know that Kallus' name was a play on the word "callous", right? To reflect a cold and unfeeling personality, yeah?
However, there's another word quite similar that has a very different meaning as well...
And once you consider those last two definitions, it makes a whole lot more sense that he wound up in the Rebellion.
I am by no means defending Dave Filoni, or anyone else in Lucasfilm. I just found this to be very interesting.











