I've never met an openbsd/freebsd, solaris or old school unix sysadmin that didn't have a total mastery of C/++ and scripting like perl. By total mastery I mean debugging and even reverse engineering binaries looking for something that was eating memory, and often completely rewriting some major program parts to add security like old smtp and sendmail. The Sr admin I worked for could quote K&R by memory and was a much better dev than the software engineers there just he was a total neckbeard and didn't want to deal with "politics" so confined himself to the sysadmin dungeon. He made more money than them too

Just look at openbsd-dev mailing list. Most of those guys are sysadmins, like the guy who wrote OpenBGP from scratch, the pf maintainers... basically all Berkley forks were created by sysadmins.