Bottom line: if you are not a "controlling" shareholder, you can exercise special rights as a shareholder (such as a right to veto a deal) given to you by the terms of your investment without having that action second-guessed as being allegedly inimical to the best interests of the corporation and its shareholders on some theory that you breached fiduciary duties owed to the company (the ruling held that no fiduciary duty is owed in such a case). In other words, when it comes to exercising special rights given to them by a startup in connection with their investment, investors can freely act in their own self-interests without regard to its impact on the company.
This is primarily of interest to angel and VC investors (who might have a direct financial stake in such matters) but also to founders who need to understand that, when special rights are given to investors, they may be freely exercised against what the founders perceive to be theirs and the company's interests (therefore don't give these rights unless you intend to live with the consequences).