This is a method of avoiding the CDU message “UNABLE 280 KTS AT OAKES” from appearing, but as this is a STAR, specifically the OAKES2 into OAK if I’m not mistaken, that is a “hard” speed restriction (cross OAKES AT 280 kts and between FL320-FL240). This method would not comply with the STAR restriction if the descent speed is lower than 280 kts on the DES page and not adjusted.
