They hired you just because

they need somebody speaks Chinese in their US team. Just like they wanted the guy in China speaks English.

Based on what you have described, your company is at the stage of selling products to China either through supply chain partner or through "agent", "representative" or"dealer". They are not ready to establish their own presence in China yet, they have not plan to set up a local sales office and hire their own sales force, nor will they need a local partner. So your previous suggestions were too early. Down the road, they may need both, they may eventually set up operations in China to develop and make product there, but it is in the future....it is the roadmap and strategy....

Even a company want to establish presence in China, the first choice is to have wholly owned company not JV, because the latter will make decison process difficuly and complex.