X11 extension libvnc.so ignores configuration parameters

Hi, I use Fedora 30 Xfce desktop. I would like to use X11 extension libvnc.so for VNC access. I have modified default config file /etc/X11/xorg.conf.d/10-libvnc.conf like this:

Section "Module"
    SubSection "vnc"
        Option "SecurityTypes" "None"
        Option "localhost" "1"

Now, when I restart Xorg server, the module “vnc” is loaded and the Xorg server starts listening on port 5900.

From /var/log/Xorg.0.log:

[ 189.014] (II) LoadModule: “vnc”
[ 189.014] (II) Loading /usr/lib64/xorg/modules/extensions/libvnc.so
[ 189.037] (II) Module vnc: vendor=“TigerVNC Project”
[ 189.037] compiled for 1.20.5, module version = 1.0.0
[ 189.037] Module class: X.Org Server Extension
[ 189.037] ABI class: X.Org Server Extension, version 10.0

$ netstat -tulpan | grep Xorg
 tcp        0   0*            LISTEN	2829/Xorg
 tcp6       0         0:::5900         :::*            LISTEN	2829/Xorg

That’s OK, but the Xorg/vnc ignores any configuration parameters. So, e.g. the server is listening at all interfaces, not just localhost.
If I try to set that parameters at runtime using vncconfig, it fails out. I tried both, root and regular user, to run the command.

$ vncconfig -get localhost
$ vncconfig -set localhost=1
setting param localhost=1 failed

I have refreshed all selinux labels with restorecon as selinux is often source of my troubles, but apparently, this is not that case.

Can anybody help me to resolve this issue?