for example, we could provide some level of commercial support for Linux audio stuff from CSIRO, but we could only focus on a small domain (MPEG audio, vorbis, sweep, and custom engineering related to analysis) and can't possibly list ourselves as providing general Linux audio tech support. We're primarily a research agency and any external work we take on needs to be somehow relevant to our projects. I'd imagine there'd be a large number of people who similarly wouldn't be willing to list themselves for general tech support, due to only having limited skills or interests, or simply for commercial reasons.