Read through the manpage for xorg.conf. You may need a ServerLayout section that references "Default Screen".
A Screen section is considered ``active'' if there is a reference to it either from the command line, or from an active ServerLayout section.
However, the ServerLayout section indicates that it is needed when you have a multihead setup. Perhaps a "no head" setup needs a ServerLayout as well.
However, remember that when you run apps remotely, while they run on the server, they are displayed by the local X server. The app is the client. The X terminal is the server. Are you looking at the correct xorg.conf file?
You could log in using ssh and have individual programs displayed. You don't need to run the server in the graphical init mode.