It's an interesting setup but will need some work, both from WOTC and Commander players for it to work.

A couple issues I've noticed. First, there seems to be a large gap between the 3rd and 4th brackets. Not sure how to close it but there should be less of a divide.

Also, just looking at the decks I've built, and going strictly from the rules, I have 1st bracket decks that could easily beat 4th bracket decks. Obviously he mentioned 'bad actors' but, at least at my LGS, most players are not going to alter existing decks more than a few cards to fit x or y bracket. So, this will create some misunderstandings when someone sits down with a powerful/optimized bracket 1 deck, it just doesn't have tutors/extra turns/combo's/game changers.

It's a good start but the pre-game conversation is still the best best. Just another tool I guess.

It doesn't need a tribal subtype. This would probably be broken with some pirate shannigans.

Orzhov (black and white) would be my recommendation. You have Eriette of the Charmed Apple, Kambal, Profiteering Mayor, Kambal, Consul of Allocation, and Elas il-Kor, Sadistic Pilgrim. All of which drain your opponents while gaining you life. Each has a unique way of winning without swinging.

Second best options could be golgari's Dina, Soul Steeper or Slimefoot, the Stowaway for Aristocrats build. Izzet (red/blue) or any spell slinging deck with a bunch of Guttersnipe effects are also solid.

Some black cards to consider, Hissing Miasma effects (of which there are many), Koskun Falls, or potential blanket protection effects such as Grave Pact or No Mercy.

Green has Elephant Grass and plenty of death touching deterants.

White has Peacekeeper and Sphere of Safety.

Blue has Dissipation Field and Propaganda.

Red has Kazuul, Tyrant of the Cliffs plus all of your Guttersnipe effects as mentioned above.

You can easily make a deck that kills (or mills) people to death without ever swinging. Just depends on the flavor you want to do the murdering with.