The work of Matsuura et al. [Phys. Rev. D 72, 123505 (2005); astro-ph/0507439] claims that heavy nuclei could have been produced in a combined p- and r-process in very high baryon density regions of an inhomogeneous big bang. However, they do not account for observational constraints and previous studies which show that such high baryon density regions did not significantly contribute to big bang abundances.