Can good developers be good CEOs?

Both roles are 180 degree apart. both needs very different skillset to deliver awesomeness. Having said this, you cant judge if good programmer will be a good CEO or not untill he functions as a CEO or if he had previous experience of being a CEO.

If the good developer has good management and business skills then yes they can.

From a sample size of one: there exists a very famous developer-CEO: Bill Gates

Can they be? No, they are programmers. Can they become? More interesting question!

they can't...