It weakens the argument considerably, but doesn't entirely invalidate it. It's not as good for career MNKs, but it *is* helpful to non-career MNKs who have their combat skill merits tied up elsewhere. With either 0 or 4 H2H merits (rare to see any number other than 0, 4, or 8 in that category), the torque *does* allow them to break a new tier.
Granted, why a Faith Torque would be going to someone who had MNK that far down on their list of things to merit combat skill for, is beyond me. But the DMG increase would nevertheless kick in, in such a situation.
But otherwise, yes, I'll amend my previous assertion - for most MNKs, with a reasonable assumption of 8 H2H merits, the torque doesn't shine for them any more than the other torques (aside from the other two that I already noted) shine for other jobs. In other words, edges out PCC but not *that* hugely.
EDIT: Also, Wiki contradicts your math, and says that base DMG is skill * 0.11 plus 3 (and then you presumably take the floor of that, although it doesn't clearly state it).
http://wiki.ffxiclopedia.org/Category:Hand-to-Hand
The end results are, however, similar, although in practice it's more like 9 skill per 1 DMG, and occasionally (every 11th tier to be exact) 10 skill. It's true, regardless, that the torque doesn't allow for breaking a new tier even so. My own math, plugging in that formula:
276-281 skill: 33 DMG
282-290 skill: 34 DMG (3 merits, or 0 merits + torque, to reach tier)
291-299 skill: 35 DMG (8 merits, or 4 merits + torque, to reach tier)
The next tiers, theoretically, come at 300, 310, 319, 328...