You are correct that the CEO cannot favor investors due to SEC regulation and simple fairness. However, the issue raised is that companies use these regs as an excuse to draw the curtains and provide less information on the whole.

This is bad for economic decision making on the whole. For example, it leads to greater volatility and securities prices that don't track value. It also places managers into a kind of priesthood with privileged access to information. Abuses ensue.