It may be that Steve Jobs email account is monitored by one or more personal assistants, who act as a human filter for importance. The private API question seem

It may be that Steve Jobs email account is monitored by one or more personal assistants, who act as a human filter for importance. The private API question seems important, and they could raise that issue to Jobs' priority inbox. Of course, the account is also accessible by Jobs himself which explains the responses to emails that seem unimportant.