My understanding (based off inference, I have by no means looked at code and am not an authority on how CoH works) is that buffs to a character, such as Damage Bonus, To Hit Bonus, Recharge Bonus prior to MM pets ignoring recharge enhancements, defense bonuses, resistances and the like, would not transfer to MM pets. Similar to how if thermal radiation hits an MM with Forge, none of the minions are getting the damage/toHit buffs because that's done as an effect to the player, not as an enhancement to the power. Likewise, I don't know that any power with a psuedo pet would actually get the effects of that toggle, because the pseudopet itself wouldn't have the toggle running, so my assumption is that Bonfire wouldn't actually have reduced KB anyway.
I guess you could make the toggle an AoE similar to Supremacy, affecting only MM's owned henchmen (and other spawned pet entities like time bomb, trip mine, but exclude from bonfire?), with an exceedingly large range and no LoS check or something? Or maybe coded similar to spirit ward, a toggle that maintains the buff on all MM pets that were nearby when activated. I'm not sure, but both feel like square peg -> round hole solutions, it'll work if someone bashes it enough but it's not going to be pretty when it's done.