The arXiv preprint by Matteo Crismani frames Mars as a post-habitable world whose atmospheric isotopes encode the loss of surface water, offering a template for desiccated exoplanets. Yet this view rests on the unexamined premise that Mars hosted sustained liquid water long enough for meaningful biological evolution. In reality, MAVEN-derived escape rates (Jakosky et al., Science 2017, n=~5 years of orbital data) indicate rapid atmospheric stripping within the first 500 million years, while Curiosity mineralogy (Grotzinger et al., Science 2014, limited to Gale crater samples) shows only transient lakes rather than stable oceans. The preprint's chemical fingerprints therefore describe a brief wet window, not a lost Earth analog. This undercuts core assumptions in astrobiology that equate past water detection with long-term habitability and narrows target lists for missions such as Mars Sample Return and the Habitable Worlds Observatory. Exoplanet surveys must now prioritize atmospheric retention metrics over mere water signatures to avoid similar misclassifications.