There were several responses like this. Once disclosed (told to someone else), there is no basis for a claim; McDonald's could freely use any idea so given that was not legally protected or which was not provided under a confidentiality agreement. Also, the Asian company might already have a patent on the process, and since all major corporations patent in all countries, it would already be available for license or, they could choose not to do so. And even if not patented, if it has been available for a while there is an "on sale bar" that prevents it from being claimed--it's like it's in the public domain. So there is some other reason--like they don't want to be bothered dealing with everyone; they have their own research.