^^^ This is typical rebel attitude. Some, like Rockstar, are smart enough to know that outwardly hating on Mullen makes them look bad. So they play the "oh I like him, he's good for the rivalry" card, which is also BS. It is a passive-aggressive jab that says, "Look at us, we're above you and eh, you're a little relevant but we're still big brother". Or similar, just use your imagination.
Truth be told, no, they don't like Mullen at all. I will freely admit I'd prefer for Ole Miss to suck forever. But on the other hand, that also allows you to get complacent. But even still, even though competition lifts everyone, when both start to get good, the vitriol really flows and they tear each other down, because they are fighting over the limited resources in the state to begin with. Rinse, repeat.