The concept of LCO combat rules feels anathema to me. Sure, effects and such can easily be created for LCO behavior, but I feel there are core aspects of a National level game that should be the same across all chapters. To me, those core aspects are: Races, Classes, Skill, and Combat Engagements. There should not be LCO races, LCO classes, LCO skills (or LCO skill costs), nor do I believe there should be LCO rules on how to engage in combat (i.e. Flurry vs. No Flurry). If Flurry is not integrated into the ARB, then players should not be able to ignore attacks/effects that exceed whatever LCO Flurry limit is in place.
In my opinion, the only legitimate way to implement the option to have alternate Combat Engagement rules is to establish Alternate Rules. These rules would then be posted on the Chapter's website and announced before game-on. Kind of like the settings for a computer game, "Here we use the Flurry Rule, the Create Undead stops you Death Timer rule, and the Earth Scholar Healing/Chaos Wand Rule". If they are codified in the ARB then people can understand what "settings" are in place at that chapter rather than each chapter having their own page of alternate rules in place; that can potentially get cumbersome to a traveling player that has to learn all the different LCO rules and the nuances between chapters ... "There they use the Flurry 3, here is Flurry 5, and that other place Flurry 3 for melee and Flurry 2 for magic/alchemy".
However, implementing Alternate Rules is currently unprecedented in Alliance (even though many chapters have had LCO rules that alter existing rules or create new ones over the decades Alliance has been a thing). And Alternate Rules would be counter to the perceived target of the 2.0 rules to reduce complexity.