The IARU approved GENEIS-A with an expected mission lifetime of  4-5 hours, and it looks like in actuality the mission will be 2 hours.   With an ERP of 75 microwatts and the possibility of only 2 short passes over any given earth station, the possibility of QRM to terrestrial users is pretty much nil.

It is easy for me to imagine that the mission designers chose frequencies and modes that would be familiar to the most potential users.   Of course one could select or design"better" modes in terms of ease of decoding, but getting casual users to have appropriate software available to use such modes is a non trivial endeavor.   Don't you remember the resistance to using forward error correction on AO-40 telemetry a couple of decades ago?   And that resistance came from motivated and technically advanced users!

de KM1P Joe