The main reason is cos other countries were. If this had kicked off in Europe, there is no way we would have locked down...nobody had any idea it was even a thing.I believe the Chinese state are spreading misinformation about the virus and lockdowns, but I'm not entirely convinced that that's the entire explanation for other countries locking down.
Why is this suspicious? They were reporting preliminary results in May, and I assume the trials must take at least several weeks. It was known to be a pretty nasty bug back in January.