There's no financial reason to hold back on developing and manufacturing the MIC "World Car".
With a China design studio, Gov't and State Bank backing, and multiple Chinese cities clamouring for the next Tesla Gigafactory, there's really no precondition of rollouts of other Tesla vehicles before this project.
What's more, the intended "World Car" would tap into a potential market of millions of units per year, and not just for China (as the project name implies).
Finally, if there is an economic downturn over the next several quarters, that is the ideal time for Governments to invest in large infrasture projects as stimulus. The fact that both China and Tesla wanted to do it already is a bonus.