From reading the article, there is no reason why Android was chosen specifically. So this experiment could have been done with any modern smartphone out there, they just happen to choose a couple of android phones. Is that right?
For instance, most other major options (elephant in the room being Apple), have onerous terms for their accessory development kits which would preclude that. Last I checked, Apple even keep the Dock port pinout "confidential" from people not in their accessory dev program, which would be a show-stopper since presumably this uses the dock/USB port for control.
All the sensors one might want on a Satellite (motions sensors, cameras, magnetic field detection) are all built into phones now. Android (or more to the point Android's Linux kernel) is specifically compiled to be compatible with most of that hardware. So less work for them as opposed to using another version of Linux.
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.