The arXiv preprint (Tomlinson et al., 2026) reports lab experiments exposing TiO2-coated surfaces to 2–10 ppm CH4 under 4–59 W/m² UV-C, yielding peak 24.4% conversion and 0.013% apparent quantum yield at the lowest concentration. A kinetic model fitted to these data and validated against prior HCHO and NOx studies predicts ventilation-scale efficiencies collapsing to ~0.017% because thin boundary layers and millisecond residence times starve the reaction. This preprint status means findings await peer review and independent replication. The work correctly flags that net-negative CO2e is possible only when pre-existing UV-C lamps are used, avoiding new electricity and catalyst manufacturing burdens. What prior coverage missed is the direct tie to post-pandemic ventilation upgrades already underway in schools and offices: those systems routinely run UV-C for pathogen control, creating zero-marginal-energy platforms for trace-gas oxidation. A 2023 Environmental Science & Technology field study on hospital UV-C retrofits showed 30–50% energy overhead when lamps were added solely for air cleaning, underscoring the leverage effect modeled here. Similarly, a 2024 Nature Climate Change analysis of methane removal portfolios ranked building-integrated approaches highest for near-term deployability precisely because they piggy-back on existing fans and lights. Limitations remain: the model assumes ideal catalyst longevity and neglects humidity competition and byproduct formation at scale. Still, the pathway is concrete—target the 10–15% of commercial buildings already equipped with upper-room UV-C and monitor real boundary-layer mass transfer under typical airflow regimes.