In 2008 Starbucks agreed with the UN to embed human rights into their business practices. That means no human should be subjected to any type of discriminatory practices, such as Christmas, and their business model should include inclusion and diversity. After all, if a person holds a different religious belief it is an offense to their beliefs. According to the UN every human has the right to not be offended because we must have inclusion and diversity. That concept was included in Starbucks response to the controversy. In fact, under "Responsibility" UN values are clearly outlined such as conservation, climate change, reducing waste, and global responsibility. Why, they even have LEED certified stores, a program of the UN non-governmental organization United States Green Building Council (USGBC).
This is just one small overt example of how a business partnership with the UN works. UN objectives are implemented through the business. In this case promoting human rights and diversity.
You see, it isn't the p.c. culture, it's the UN.