Fully agree on no factory in China.
According to news reports, previous talks ended when Moderna refused to share IP and/or to produce in China with a Chinese "partner" (aka spy). I doubt Moderna will even budge on that position.
I suspect China came back to them because they have abandoned zero covid policies.
Consequently, they have and will have plenty more covid cases AND they need to cut down on hospitalizations without an effective home grown vaccine.
Surely China has tried to reverse engineer from a vial of Moderna vaccine and, to date, have failed. Now with cases rising rapidly, they really need an effective vaccine. Problem is, China's MO is to steal the technology to make it with slave labor on the mainland.
From Moderna's standpoint, they have excess manufacturing capacity that is costing them money to produce nothing. A Chinese order for 500 million doses or more would solve the excess capacity problem.
Fortunately, Moderna has enough cash to call China's bluff on the IP issue. Nevertheless, one billion doses at 20 per dose = 20 billion in revenue. No question Moderna wants such a deal but they won't give up their secrets to do so.