This 2026 arXiv preprint develops a quantitative framework to quantify uncertainty in abiotic chemistry on ocean worlds, using Enceladus as the primary case study for two candidate biosignatures: carbon isotope ratios linking CH4 and CO2, and amino acid chirality. The approach models overlapping abiotic processes such as hydrothermal serpentinization, radiolysis, and ocean transport timescales rather than relying on single measurements. Because the work is a theoretical modeling study without empirical samples or spacecraft data, its conclusions rest on parameter ranges drawn from Cassini plume observations and laboratory kinetics. It demonstrates that current uncertainties in temperature, lithology, and initial organic inventories are large enough to produce false negatives for both isotopic and chiral signals. Complementary geophysical constraints to roughly 10-100 °C internal temperatures and better rheology constraints are therefore required. Earlier coverage of Enceladus plumes largely emphasized the presence of organics and silica without systematically propagating abiotic variance; this framework fills that gap. Related Cassini INMS and CDA datasets (Waite et al., 2017, Science) already hinted at CH4 variability, while recent Europa Clipper planning documents stress the same multi-instrument integration. The preprint correctly flags that neglecting the abiotic baseline risks both over- and under-interpretation, a point missed in many mission concept papers that treat any deviation from equilibrium as biogenic.