US citizens living abroad must file US taxes. Are you saying they can't use TurboTax?
This thread is over 5years old since anyone posted in it. You'd be better-served to start your own new thread, so it will show up as a new issue to the forum, who can answer questions you have about US citizens using TurboTax from abroad. To do that go the link below:
Use the top box there to summarize the title of your issue. Then there is a box below that with more room for details, if needed. This is a public Internet forum, so don't post any personal info..