He would only promote the most loyal and those who brought Cobra profit, and his followers would be okay with that because they can also be loyal and give cobra profit. "Anyone who are willing to fight for money and power are welcome to take up an rifle and fight alongside him". The promoting only the one who are usefull are the meritocracy part of the idiology.
The "election process" are like a direct democracy where the most powerfull claw their way on to the top and the others agree they belong there because they dont want to loose their position in the pack order.
In the Starship troopers movie there is a funny moment (one of many) where the general whos strategy had failed steps down and let another general step up as leader. I dont think Cobra Commander would done that heh heh heh.