The opinion is quite readable. Essentially the judge says that he's only applying that standard (called the Unocal test) on "defensive actions by a target corporation’s board of directors in a takeover context". On the action that didn't fit that profile, despite being potentially harmful to eBay, he deferred to their best judgment.

I'm no lawyer, but the way I read that decision is: do what you think best, just don't purposefully mine the field against one of your shareholders.