If they did try and hand it back, it wouldn't be $140b.
http://www.zerohedge.com/news/2013-02-07/einhorn-will-not-take-it-anymore-demands-aapl-buy-his-stock-higher-prices
If i understood the articles right, they take profits before they've paid tax, and dump it into the stock market. To pay it out to shareholders they'd have to sell off whatever they put it into, pay tax on the profits, and *then* send out the dividend - will be interesting when it happens but doubt any time soon!