The government will get the money eventually through increased taxes or through printing more money and deflating the value of the apple "cash" pile. All the Government has to do is to print money and they can take Apple's money without Apple being able to do anything about it!
Nothing says Apple must keep the money in the form of US dollars in a bank account. If it's sitting in any kind of investment that tracks inflation, printing money won't take the money. If they choose to keep it in other currencies, printing money won't take the money.
