It is not only that Chinese labs can undercut on price. It is that they must. They must give away their models for free by open sourcing them, and they must even give away free inference services for people to try them. That is the point of the post.
There is not ‘must’ here, they did not ‘have’ to undercut every other strategically and technologically important industry the rest of the world has, but they did as a point of national policy.