Apple has more than enough money. More than they'll ever need. It's actively employing strategies to avoid taxes. I think they can afford to do some public service from time to time, even if it means (in absolute numbers, massive) losses (if you don't count the value of having done something good for the people).

I'm not saying Apple does nothing for the open source scene. In fact, they're maintaining some important projects (like WebKit). But when you have billions of dollars that you don't know what to do with stored in some offshore haven, you could do a bit more.