Non-US based Amazon Associates must "perform all services" outside the US

An interesting addition to Amazon's terms and conditions for their Associates (announced here):

“If you are a Non-US person participating in the Program, you agree that you will perform all services under the Operating Agreement outside the United States. If, for any reason, you cannot comply with this requirement, you must notify us using this link for an exception.”

My guess is that this is something to do with tax-regulations, and is worth a few moments thought (at least) for Bloggers who use Amazon Associates links to earn money from their blogs.    

But it also made me wonder about bloggers who travel a lot:   we possibly shouldn't be doing any work inside a country where we don't have a visa that allows us to work.   I wonder if that includes writing blog posts, or perhaps even drafting but not publishing them or taking pictures for them?