Maybe I read the article incorrectly, but it specifically states that income derived from foreign businesses is tax-free. So this should include any freelance work or employment with a foreign entity as well as business profits derived abroad. I don't think the "butt in seat" rule applies here.

It is a good idea to bring this up in any case, because there could be other tax implications, especially for Americans unaware that they will be paying tax on income above $108,700.