Why is this distinction even relevant? Facebook then needs to pay its employees more to make up for the difference. No matter who the government taxes, everyone involved will shift their habits to compensate for it.
In addition, isn't the whole point of corporate taxes to provide money to the country in which that business is making a profit? We may live in a global economy, but we don't all live in a single country. Businesses should be taxed appropriately for their revenues in a country or not be taxed at all. Saying that it's okay to avoid paying taxes because you can afford to move money offshore is hardly a level playing field and gives money to countries based on their advantageous tax codes, not to the profits achieved in that country.