Tsai is simply passing through the US, and her so-called trip is an unofficial visit, consistent with US-Taiwan relations. Any tension or military conflict caused by Tsai's visit would be an outlandish escalation on China's part.
China has made its case to the US about why meeting with Tsai would be a provocation, and if the two countries go through with it, they’ll be risking the lives and well-being of the people of Taiwan and undermining the "One China" policy. This trip, posturing as an innocent "transiting through," shouldn’t happen.