Well... there's something of a territorial dispute over the existence of Taiwan - it's claimed by both the Republic of China (which moved its government there after the Communist Party took control of China in 1949) to whom the island was ceded by Japan at the end of WW2 and the People's Republic of China (or "China") which claims sovereignty over all Chinese territories. Most countries don't recognise the existence of Taiwan as an independent nation for fear of pissing off China and Taiwan's attempts to be recognised by the UN are perpetually blocked by China - because they say they own it and the UN resolution recognising PRC as China means the issue is settled..
A number of different flags represent Taiwan as a separate entity - as ROC or as Chinese Taipei - while China say that the Chinese flag does, and I imagine that PD didn't want to risk putting in the wrong flag and annoying China.
