Boyd, a bit of his spark already returning, asks what would happen if he were to kill Johns right at that moment, but Johns informs him that his friends would destroy everything Boyd loves in return. That threat being enough to stay Boyd's hand for the moment, he folds the crude map and pockets it...
...and then we cut to the prison barber, who's enjoying an empty shop until a guard enters with Arlo in tow. The barber says something or other about him not being scheduled before waving his hand in front of Arlo's apparently catatonic eyes, but the barber's comments and actions aren't really relevant, given that from behind him, Hunter soon hits him twice with a sock full of coins or whatever, knocking him out. Arlo doesn't even blink as he sits still in his chair, and the guard wonders if Hunter shouldn't hit the barber once more for safety's sake, which isn't going to be necessary here but is still advice that's going to look a lot more solid in a couple minutes. Looking at Arlo's motionless expression, Hunter asks the guard what he gave him, and the guy replies that he just doubled the meds Arlo was already on -- that way the tox screen won't look suspicious. He goes on that they have about five minutes before someone notices that the cameras are off, so he's going to wait outside for Hunter's knock, at which point he'll "come in hard" and pull Hunter off Arlo; he then wraps it up by reminding Hunter that their story will be he slipped in behind the guard when he went to the men's room before telling him he's looking at some serious extra time. Hunter, however, merely replies that he'd like some privacy now, and when the guard's gone, Hunter pats Arlo on the head and tells him it's nothing personal before heading to the rack of scissors on the wall.
And before I forget, it seems unlikely Thompson is doing this to protect his deal, for two reasons: One, he could just have told Raylan when he asked and beaten Arlo to the punch, and two, committing murder would seem to complicate the possibility of a release. Of course, you could argue that Arlo committing murder didn't seem to hurt his chances of a deal any, and also speculate that maybe Hunter knows who Drew is but not where he is, but I still think it's more likely that Hunter is protecting Thompson. After all, Arlo killed the trustee over a bag connected to Thompson.
Oh, and speaking of Arlo, as soon as Hunter's back is turned, he drops the catatonic act and is out of the chair quick as a cat, whereupon he grabs a handy bottle of Barbicide and smashes it across Hunter's face, in case you needed any convincing that Arlo is old-school. Hunter, crying out and bleeding freely, manages to backhand Arlo in the face, but Arlo's next weapon of convenience is an electric razor, with which he pummels Hunter into submission. On the floor, it's clear Hunter is reeling but not unconscious, and I wonder if Arlo doesn't want to queer his own potential deal by committing another murder here? Or maybe he's just worried that the guard will kill him if he returns.