Again, 50,000 employees who are bound to follow the company's directives about disclosing events that happen in the course of employment whether it be meeting with your boss, viewing an unreleased product, attending a Friday beer bust, or reviewing quarterly results.
It doesn't matter if there were 5 or 50,000 employees invited to the event. If the company says it's private, it is.
While this was not a family event, I'm guessing that Apple's senior management team would be willing to abide by the family wishes concerning public disclosure of the event. Could they say "Screw you, Laurene, we're posting the entire video to the Internet, whether you like it or not because we have lots of fans/customers/shareholders who want to enjoy the festivities and commemorate Steve's death."? Yes, they probably could. Will they? Probably not.
Again, 50,000 of Steve's team members who followed company directives to draw drapes, lock retail stores, etc. and keep it as an internal-only event.