Do you know if a PRC passport holder with a Taiwan travel card can transit in TPE leaving China?

I know someone who says he did it earlier this year, but I am now wondering if it was "self connecting" on two separate tickets. I don't even know that you can issue a single ticket leaving China and transiting in TPE. I had one years ago, a Star Alliance RTW fare, and was told at CA check in at PVG that was an illegal routing. They eventually let me fly saying China immigration may stop me but they did not.