"What would stop a major from directing another company that is not directly affiliated with them, but has been set up in the past, or is now being "courted" by a major, and will make a good dollar if all they have to do is buy shares of NOT and hold them, and vote with a major if and when they are directed to do so?"

What should stop any group/individual would be the term insider trading.  To also collude with with another company to manipulate a voting process for insider information further compounds the crime.  Not saying it doesn't happen, but it would certainly be something not to take lightly.