While LFS is capable of mounting network file systems such as NFS these are not mounted by mountfs init script since the tools needed to mount these systems may not be available on the root partition and also since network file systems need to be mounted after the networking is on and need to be unmounted before the network goes down.
Install the /etc/rc.d/init.d/netfs network mount script included with the blfs-bootscripts-5.1 package.
make install-netfs