In a recent paper, Wicht, Lämmerzahl, Lorek, and Dittus [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.78.013610 78, 013610 (2008)] come to the conclusion that a molecular rotational-vibrational quantum interferometer may possess the sensitivity necessary to detect gravitational waves. We do not agree with their results and demonstrate here that the true sensitivity of such an interferometer is many orders of magnitude worse than that claimed in the paper.