At which point the satellites can no longer be open source. Perhaps more importantly, Android already runs on the Nexus S; VxWorks doesn't. It defeats the purpose of using commodity hardware if you start over from scratch on the software running it.
I agree VxWorks would require additional porting effort. I also think that Android was the right choice for this mission.
I'm not sure I agree with the implied high priority placed on open source. The relative development costs of android, real-time linux, or even a commerical RTOS are noise in the flight software development budget. Reducing the cost is a more important driver to making space more accessible.
The big benefit, if these android cube sats fly successfully, would be to retire a lot of risks - thus opening the door for future programs to fly with android.
