I think they are just showing Negan is more of a three dimensional character than a lot of people would like to admit. I don't think he's good, but he isn't pure evil either. The whole reason he ambushed and killed people from Rick's group was because Rick had killed a whole bunch of his men already. Granted, we can argue Negan was already the aggressor (to Hilltop, and other groups) to all the groups they were subjugating, but the fact that Negan is so miffed about what Simon did even after the garbage heap people were like, quadruple agents? Says a lot about him that he still didn't want them all dead. He's misguided, for sure, though.