The use of redundant I2C in spacecraft avionics
Yes, there is a length limitation with I2C but I think what they may be intending this for is to communicate with other ICs on the same board or boards located within the same subsystem rather than thinking about communicating with sensors deployed around the spacecraft and other spacecraft related systems. Most ICs today will incorporate I2C while data rates and distance can be seen as limitations, for onboard communication with other ICs it yields an extremely reliable method of data transfer and control. ICs such as power management functions (PMIC), onboard temperature sensors, MEMS-based accelerometers and gyros, to name just a few, I2C is a viable contender.