Marr didn’t hate the Jedi— if anything, he respected them for being warriors —but saving one of them wasn’t something he had imagined himself doing. He wasn’t like the other Sith on the Dark Council— didn’t care for all the scheming, plotting, murdering, and anything else they were up to —which is the only way he’s able to come to terms with the fact that he had saved a Jedi padawan.
You were young, completely in over your head, and had almost died trying to do who knows what. He had half a mind to take you back to the Jedi, but he… keeps you instead, right in the safety of his ship. It was dangerous for you to be running around without a Master, and he wasn’t going to let you go just so you could end up killed, or seriously maimed.
“Calm down, kid.” He dodges yet another chair that you throw at him, having tried calming you down ever since you woke up in his ship’s medbay. “I’m only trying to help you.”