He means socialism is a non-Chinese idea, coming from Germany and Russia, though certainly syncretized to fit Chinese society.
On the other hand, he's mistaken about China being a traditionally trading power; that's far from the truth. Though trade was necessary, and outsiders always desired to trade with China, up until the 1980s trade has been frowned upon, even into ancient times. Merchants were highly disrespected in pre-communist Confucian China, and the only reason folks became merchants was to afford to educate their children in the hopes they could join the bureaucracy, admittance into which was based on an imperial examination. Bureaucrats were extremely powerful in pre-communist China, serving a function like aristocracy or nobility in Europe.
Furthermore, those that did become merchants generally peddled wares from village to village, within the same province, long-distance trade was very unsual in pre-industrial China, until the arrival of the Westerners.
And yet furthermore, even when the Westerners did come, they were forced into little port cities like Macao (a swampy region mostly uninhabited when the Portuguese arrived), or Hong Kong (which was granted from war). China refused to import anything from the West except silver, and most of the silver came from China itself through the blackmarket in exchange for opium. The major exports of China were tea and silk, naturally.
This is why during the Victorian period and thereafter so many westerners (and Japan) attacked China to gain access to trade ports, the Chinese were very unenthusiastic about trade outside of China.