I think it would have been cooler if Bob had been bitten and those dbags had eaten his infected leg. (Yes, I know everyone's infected but something about being bitten seems to hasten the process)
I also think Gareth is full of crap about it not being personal. There were plenty of dead people back in Terminus they could have eaten. Like his Mom.
I wouldn't be surprised if Bob ends up revealing a bite or scratch in the next episode... it would explain why he left the church to go off alone. Plus it seems like the producers love to have an ambiguous setup leading to a "surprising reveal" later on, like the guy Tyreese "killed" at the cabin showing up at the campfire Bob-B-Q.
I somewhat disagree about the whole "nothing personal" bit. After the systematic slaughter of those four guys at Terminus and the casual attitude of the Termites, I can believe that they have become totally "shut off" and view other humans solely as food. That makes Gareth and the others much scarier, as they have pretty much become living versions of the zombies... focused solely on food and unable to be reasoned with. Though I will say I think Gareth is taking pleasure in hunting Rick's group after what happened at Terminus.
Is it me or did it seem like Bob and Gareth had a history, beyond what recently happened at Terminus?
I didn't really get that vibe, but it is an interesting idea. My thinking is just that Bob had talked/pleaded with Gareth while his group was captured and in the train car prior to Rick's arrival. It could be interesting though if it ends up being revealed that Bob had passed thru when Terminus was a real sanctuary, or if he was a resident who had escaped when that hostile gang invaded.