There is a difference here between karma and the hypothesised karma points.there is nothing about meta-game resources that violates a simulation; that tension is purely an artifact of his assertion that "coherent" play is superior. "Karma" only violates a simualtion of a probabilistic world, which, guess what?, heroic fiction is not.
There is no issue for simulationist play if fighters have powers like "Cleave Mountain: when you use this power, the top falls off a mountain." This would resemble many traditional D&D spells.
When the fighter starts to have karma points, however, that the player of the fighter may use to start changing the ingame situation in various ways, then it becomes a potentially different matter. If all the karma points do is eg provide a temporary bonus to defence or attack, it's probably not a big deal - and in fact these probably wouldn't be metagame mechanics in the relevant sense, as they would represent the fighter in question exering a heroic effort, or perhaps being the beneficiary of the forces of luck in the universe.
But the more open-ended the karma points, the more the threat to simulation, as they allow the player to control ingame events in a way that fails to respect hitherto-established ingame causal logic. Come and Get It is 4e's poster-child for this.
In practice, Come and Get It has produced widespread calls either to reintroduce ingame causation as modelled via probabilities (the frequently-mooted attack vs Will), or to allow the GM an override in order to preserve the integrity of the ingame situation (so Come and Get It works as written most of the time, but the GM will exempt, for example, the unarmed mage with only ranged attacks, on an ad hoc basis).
I think that even Hussar's mooted idea, in which the resource in question has an ingame rationale (high level fighter's attract the interest of supernatural forces) would be likely to produce widespread hostility. After all, the uniform skill progression in 4e could easily be explained in such terms (although I personally prefer to treat it as primarily a metagame-driven thing), but has nevertheless been widely criticised. Just the same as there are widespread calls to be able to play a wizard who knows nothing about swimming and has no friends among the waterspirits who help out with it, so I would expect there to be widespread calls to be able to play a fighter who has know supernatural allies but relies purely on his/her own mind and body.