It was many years since the Saurians had first learned Tai-Chi from their human friend. From there it had begun to spread through other ships, then to stations and colonies of their people. But once it hit their homeworld, its popularity spread like wildfire. Soon it became a required part of the physical education of their young, and a part of their cultural identity. Needless to say, the humans liked the change.
Of all the Human combat styles with alternative uses, Tai Chi is the most surprisingly versatile. Students of various species need a sensei who understands that not all bodies can move the same way, but it is still adaptive to need.
It's also amazingly fortifying for Havenworlders to realise that they can defend themselves against a far more fortified enemy. It was also entertaining for Deathworlders to watch with optional snacks on the side.
It's also something Humans enjoy encountering by surprise, for reasons known only to Humans. They're not often the antagonist in these cases, since the Humans favoured in Alliance space are also the Humans who get along with Havenworlders.