That's not at all how I would handle Beatdown. This isn't to say I think it's not a valid way, because it likely is, it's just not what I would do.
I like the Traps idea, but I would probably go the Pathfinder route, maybe with one hired Trap just to make sure he has a decent ring of them around him. Primed Traps are not only good for activation control and self-sacrificing, they're good for potentially keeping your ranged hitters out of melee for a little while. Little triangle of Traps around a Pathfinder (easiest one, since he can set pre-Primed Traps himself) or Sidir, or Sam Hopkins, I think there's a lot of potential there for letting them kill a few things before they're taken out.
I would probably take McCabe, but I don't agree that the relics are filler. I think they're quite important to how any Strategy is going to be played. I would favor Glowing Sabre and Strangemetal Shirt for Beatdown, because that would make him more killy and more difficult to wound. Although, I might take Badge of Speed instead the Paired goodness, because a re-activated Sidir might be one of my favorite things when it comes to bringing the pain. Plus it means a potential for two boosted Df stats, potentially very important when VP is determined by how many models are taken out. Expensive relics, but I think they're worth it.
Another great model for Beatdown is a Wastrel with Earth's Elixer. True enough that a Paralyzed opponent can't kill anything, but better, perhaps, to have a model that literally cannot be killed for a turn, guaranteed.
Austringers are a good pick for a list like this as well, because they can be safely tucked away while they peck at things. I think this could be particularly effective with the Badge of Speed relic, because 'Black Flash' can re-activate Guardsmen, too. Two 18" strikes from one Austringer in the first or second turn could be lots of fun. Pair them with a Drill Sergeant for extra shooting goodness. (Only drawback there, no Effigy. Tough call to make when healing and a resilient model are your friends.)
Lastly, I would definitely want some Ronin in a Beatdown list. They're really good at getting out of trouble and dying on their own terms. They're also decent at killing things.
Don't get me wrong, I do like the idea of Paralyzing everything, just not sure how often that can be practical. Maybe something like Coppelius (Hoffman can take him) with a Paralyze that can't be resisted by half the models in the game. But Wardens aren't always going to manage it, nor is McCabe. They're probably not even going to manage it a majority of the time. So I'd favor raw killing power and survivability. Mix and match for game size.