Why didn't Severn let go in China?

Showa Department Ultraman's works (including the first generation, Jack, Ace, Taylor, Leo and Eddie) were introduced to China on 1993 (copyright of Shanghai Yuangu Company). For some reasons, Saiwen's works were released a little later than other works, but they were also released in China. You can find the dubbed version of Mandarin on the Internet, and the VCD has also been released.