If you really are bringing the same value to the company, then 50/50 is correct. In reality, that's not likely to be the case.
The CEO needs to be the guy that holds it all together. That's a lot of responsibility, and requires some serious knowledge/education/experience/talent/etc. As much as I like to think the developer is the lynchpin in the company, it's actually the CEO. A bad CEO will destroy a company faster than a bad developer. And a bad developer is easier to replace.
As the article says, the split will depend on the people involved. There's no magic formula for figuring it out.