3.7.1... That's ancient. We're up to 3.8.0 by now. Also, you're using wxLauncher from the looks of it.
Diaspora is a TC (Total Conversion) for the FSO engine. The downloads you're using are quite old (although they're technically still the official downloads). The engine has been further developed since then so using a newer version might already resolve your issue. A launcher is generally necessary to pass configuration and options to the engine. Form your script I'm guessing that wxLauncher is bundled with Diaspora.
Anyway, the easiest solution is probably to get Knossos
. That will guide you through the necessary steps to download the latest version of the engine and Diaspora.
NOTE: You do NOT need Freespace2 to use Knossos and/or play Diaspora.
If you want to use the official download instead, you'll have to download the source code for the latest nightly
and compile that or download a finished build
and replace your fs2_open folder / the fs2_open_3.7.1 file with that.