That fellow is wrong. John Deere may now be producing engines in China (if the factory is in operation already), but it is only supposed to be for equipment built in China (unless something has changed in the two years since the press release). According to the press release they were supposed to start production at the end of 2013, so they may not be building anything there yet. According to that press release, they have factories in the US, Mexico, Argentina, France, and India. They also source certain models from other companies in other countries such as Japan and others, perhaps one of the third party models have contained a Chinese engine at some point, but it is not a typical practice for them.
The press release.