Loading up the app in terminal reports that it is missing some support libraries. After a bit of tinkering I found a quick workaround. In preferences make sure you add -nolibpng to the configuration textbox, and -nolibjpeg to the additional parameters textbox. It's unfortunate that fuhquakeloader doesn't seem to remember the additional parameters yet, so for now you you have to enter -nolibjpeg in each time you play.
Anyway it's great to see another Quake engine for OSX, many thanks to the developer!