We identify the dominant collisional decoherence mechanism which serves to stabilize and superselect the configuration states of chiral molecules. A high-energy description of this effect is compared to the results of the exact molecular scattering problem, obtained by solving the coupled-channel equations. It allows us to predict the experimental conditions for observing the collisional suppression of the tunneling dynamics between the left- and the right-handed configuration of D2S2 molecules.