I understood Natami was to be (near?) 100% compatible with OS3.1 but with extensions to access the more advanced hardware? In which case a patched 3.1 would make sense. I assumed they'd sell the hardware without an OS, users would then be responsible for OS installation (avoiding any legal complications). Most users already own a legal copy of 3.0 / 3.1 anyway. Not sure about the ROM's though?
That would be my guess as well. they'll encourage ASROS68K development as i will provide a legal OS, but the systems probably will ship w/o an OS.
This would allow end users to install whatever variant they choose.