SIM 0.9.3-r1 seems to be stable (at least for me) so is there any special reson why it is masked? Reproducible: Always Steps to Reproduce:
Development policy states that "When a package version has proved stable for sufficient time and the Gentoo maintainer of the package is confident that the upgrade will not break a regular Gentoo user's machine, then it can be moved from ~ARCH to ARCH." Sufficient time is generally a month.