Well, they did have a separate private family event already. That's clearly very personal.
But if there's something in this event that the family doesn't want to be seen, why would they be ok with 50,000 employees seeing it? It's not exactly private at that point.
Because those 50,000 chose to work for and with Steve. They have spent a lot of their lives in executing Steve's vision. They are also co-owners of the company that he created.
Even if it's a companywide event, it's still private, just like a town hall/all hands meeting, a sneak preview into the upcoming product, or free ice cream on a particular Friday at the company cafeteria.
Remember, the size of the event has nothing to do with whether or not it's public. If Google rents out Shoreline Amphitheatre for a picnic and concert for its employees, it's basically the same thing. The fact that you own an Android smartphone or that you use Gmail doesn't entitle you to attend the event.
The audience is different, larger, but still selected for this particular event, just like the Sunday event had a different audience.
It's likely that temporary employees and contractors were not invited to the service. Hell, I've been a contractor in high tech and as such I wouldn't get invited to the company holiday party.
If you want to see Apple's official endorsed, publicly viewable memorial, just visit
http://www.apple.com/stevejobs
That's your public memorial. Otherwise you can peruse the images and videos of various Apple Store sidewalk memorials. Those are public.
