That sounds right if you have systemd installed.
systemd will symlink /sbin/init back to /bin/systemd
chkrootkit probably hasn't been updated to recognize this yet, so probably thinks that /sbin/init has been hijacked by a rootkit.
What you are getting from chkrootkit is probably wrong and I would think a bug should be filed against it.
It was also reported against F14 when systemd was installed as well.