If you DON'T have local_unbound_enable="YES" in your /etc/rc.conf, this does not matter.
What I've experienced before with local_unbound_enable="YES" was that /etc/resolve.conf was updated again (commented out nameserver entries) on restart (regardless manually or after actual reboot) if any changes to /etc/resolve.conf were made.
Most notablly, when I've disconnected from wired home LAN and connected WiFi outside home, then back to home and reconnected to wired home LAN, no hostnames other than ones in /etc/hosts could be resolved.
This was because /var/unbound/forward.conf was updated to use the DNS supplied on the DHCP server of the WiFi was unavailable outside the WiFi network and I've NOT manually edited neither /etc/resolve.conf nor /var/unbound/forward.conf for home LAN, thus, no usable DNS server was available.
Not sure it still matters, though, as I'm not using other than wired LAN with fixed IP addresses for years.