"China has repeatedly demonstrated significant skill in industrial espionage. I don't doubt they have the means to pull this off, "
They've demonstrated zero technical skill in creating electronic devices capable of high speed data manipulation without a power source and without connection.
Obviously any technologically advanced country can produce a tiny IC and place it on a circuit board. But just sitting there not connected to anything accomplishes nothing.
The USA has even greater expertise and more practical experience, but they couldn't make a piece of unconnected silicon sitting on a non-conductive area of a PC board hack a system.