Self-fulfilling prophecy
This idea of hiding the succession-planning policy, saying it would undermine this and that ironically just adds to the idea that Steve Jobs is so centrally important to the company. Its exactly the opposite message of what they should be doing as a company. They would do well to slowly down play the idea that Steve Jobs is so central to the company, because if anything did ever suddenly happen to him or he simply wanted to retire, then the current way Apple have built up his centrally important status, that inflated image of him could seriously backfire and hurt their company.
Imagine if some sudden bad news appeared about him, like say he was suddenly found dead or was found to be terminally ill. The way Apple are playing it and have played it all along, such bad news could cause the collapse of their company. Their share price would we wiped out in hours.
I don't think they (the Apple top people) are doing Steve Jobs or Apple a service in the longer term by hiding this information now. They should be openly and slowly discussed what possible succession-plans are in place now, so that if or when the time comes (even if that's a decade or more from now), its not such a massive shock to the company image when it does finally occur. That would help protect the company's future.