Why might Hong Kong stop purchasing ads on Google's search engine?

A few days ago, Google decided not to remove a banned protest song from its top search results and replace it with China's national anthem when users search for Hong Kong’s national anthem. In addition, Google said that it didn't manipulate search results amid a row over the Hong Kong national anthem.

As The South China Morning Post reported on December 17, a senior Hong Kong official has warned that if a controversy over the national anthem search listings is not resolved, the city would stop buying ads on Google's search engine.