I believe you have that bit of history backwards. The console was always called the "OUYA" but the button configuration on the concept was all different coloured Os. The obvious choice was to make them all different and since OUYA was exactly 4 letters backers and OUYA staff put 2 and 2 together and so the buttons were renamed.

Talking about the placeholder buttons

Announcing the new O,U,Y,A button configuration