I think the focus should be on tools with high surface area that enforce security bounadaries. Especially those where performance is not so important. Like sudo, openssh, polkit, PAM modules. It would be make a lot more sense than these half-baked rust rewrites that just take away features. (I'm biased I personally had a backup script broken by uutils) I think rewrites in rust need 100% bit for bit feature parity before replacing the battletested existing tools in c userland. I say this as someone who writes rust security tools for linux.