My fix would be for procps sysctl and init files to not be installed at all. That way freebsd-utils is free to have its own init file. However this may impact on your arch in ways I cannot see, so here is your time to tell me if this will work for you. I won't be doing the fix as suggested in the bug report, procps' init file works fine with its sysctl.
It looks like we (GNU/kFreeBSD) have to create better wrapper around native /lib/freebsd/sysctl. The current one does not accept file name for "-p", it always uses /etc/sysctl.conf and the possibly specified filename treats as variable to set. Petr