What if a user want to buy AMIGA ONE motherboard just for running Linux, without buying Amiga OS and Amiga ROM?
Well, if Eyetech sell the AmigaOne G3-SE with a standard bios (ie, without AOS 4 exstention) then it is not a Certified Amiga Product thus does not have to ship with Amiga OS. It would be up to the Hardware Vendor to sell an uncertified version.
Same if bPlan wanted to sell Peagasos with AOS 4. They would have to get the board certified. Which would mean it would have to be flashed with a bios with AOS 4 exstentions. It doesn't mean they can't bundle it with MOS. It would just have a different bios (which I assume they have), thus no need to include AOS with the MOS version of Peagasos.
The BIOS would make it a different product.
I assume that if someone wanted to run AOS at a later date that there will be some arrangement made to flash the bios.