What the Chinese guy (He) did was completely different. He permanently altered the germline in embryos, which means that every cell in the resulting baby is transformed permanently with the change he made. The work he did violated a wide range of good practice (specifically, the change he made didn't actually work for the goal he desired, and he also ignored all the ethical advice around this experiment, and avoided getting the necessary approvals).

This research is instead a therapy used to treat an already born baby, and it doesn't modify all the cells in the body. Many cells in the body that are transformed by this technique will eventually die and be replaced by clones of stem cells which weren't transformed. I haven't read in detail about whether this therapy targets stem cells, and how long term effective the treatment will be- hepatocytes (liver cells) turn over constantly, so I would expect if the treatment did not affect the hepatocyte stem cells, it would only last ~months and the treatment would have to be repeated.