The Great Ming Dynasty has too many enemies. Beyond Li the rebel and Zhang Xianzhong, the Tusi in the southwest are in revolt, not to mention the Jiannu in Liaodong and the Mongols to the north... If one were to add Zheng Zhilong to that list, Emperor Chongzhen would have no certainty of victory.
Zheng Zhilong, in particular, is a formidable threat; not only does he command tens of thousands of elite naval troops, but he is also actively settling migrants and building fortifications on Dongfan. (In the early Ming Dynasty, Taiwan was known as Great Liukiu; from the mid-dynasty onwards, it was called Dongfan.) If the Imperial Court were to have a falling out with Zheng Zhilong and officially declare war, even if he were defeated, Zheng Zhilong could simply retreat to Dongfan and establish his own independent regime.
However, since the matter of Zheng Zhilong has been exposed, it can no longer be ignored.
Chapter 549