It gives the appearance of fraud.
If you have a private board that has the power to add and drop people at will there is a problem.
If you don't toe the line you're tossed. Someone posted they were tossed.
They could easily be accused of pumping for the CEO.
Hey, guys hold and buy some more! While they trade.
The tossed finds out who has the case and they drop a dime. Those trading records are subpoenaed. You learn they were trading the whole time.
Private boards with the CEO as a member are not a good idea.
Someone tossed wants payback so they drop a dime and the ringleaders have their trading records seized.
It gives the appearance of pumping for the CEO.
Why do 99% of day traders lose money?
They trade on a fundamental misconception about the nature of stock prices, namely that they are somehow persistent and predictable.
In other words, they pattern trade until they lose money. 99%.