from what I have read, appl has 150 Billion offshore, however for them to use that here would incure a 35% tax, so they have decided to do a bond offer because the time is right for bonds, and a great way to raise cash at home.
Just some of what I have read on the net and business sites.
There last bond offering was poor timing interest wise, however they said there was really great interest in more bonds from appl in the investment community.
But yes i fully agree they could buy us with there coffee change.