OK, let me ask something then since I'm literally right in the middle on this debate (I neither love or hate him). It seems like everyone else I've seen on this board is either completely one way or the other while I can agree with certain aspects of both sides.
Obviously he had a bad game against Buffalo considering he had multiple minors and then the hit that got him suspended. But how often before that was he really a liability? He's a the kind of player that lives right on the edge of what's allowed and what's a penalty, his job is to hit, fight, stir things up, and try to provide energy to the team. He's going to take penalties doing that and a lot of the time when he's gotten those penalties most people have argued against the refs saying he really didn't deserve it. There are times when he does deserve the penalties obviously, but personally I don't think it's often enough to call him a total liability. I think as far as penalties go I'd say Downie hurts the team a lot more, he takes them at really bad times and most of those are really stupid moves on his part. I feel like a lot of Rinaldos penalties are just him being a little too eager instead of being dirty or stupid, and usually he's not taking them at crucial times and hurting the team.
On the other side, I'd certainly rather see a player who can add a bit more skill to the lineup, even if it's a Wellwood type who isn't going to score much but has a chance to. Zac is pretty much energy or nothing since he isn't relevant offensively and isn't great defensively. You have to think, is the energy he brings important enough to the team to keep him on the 4th line? I'd say that's a decent question to ask since you can visibly see the team get pumped up on the bench, most noticeably Simmonds, when Rinaldo has a big fight or hit.
Basically, I don't buy either "He's vital to the team, we need what he brings" or "He's a liability, keep him away from the team"... I'm just not sure.