Hi @fab,
you found a bug as it seems. Get the fixed initgfx rc-script as follows:
# cd /etc/rc.d/
# fetch https://raw.githubusercontent.com/nomadbsd/NomadBSD/master/config/etc/rc.d/initgfx
Then rm -f /var/initgfx_config.id to force re-detection of the graphics card, and reboot.