You bring up some good points; what are the rules? Only what the person physically touches with their body? How much of it is turned? The physics are also a really good point; how fast does the transformation occur?

The economic and political consequences are what I had initially imagined. Nations and corporations trying to get their hands on the person, either to stop gold value from inflating or to use the person for monetary or technological gain. Gold is very useful for electronics since it's such a good conductor. I think it also has some uses in astronomics?