Don, no problem.
He may have changed his mind.
He may not have made the decision public.
No way of knowing for sure.
Being in Paris should not make much difference in being a columnist for a U.S. paper. With e-mail articles can be filed from anywhere.
Using the Internet I indexed a number of books while in Prague this winter. The publisher would email the book as an attached file, PDF format. I would index the book and sent it as an attached file, Word format.
The Internet gives us all freedoms unthought of previously.
Blessings.
However - given Carson's publicly stated beliefs, placing himself in a country that takes our current administration's treatment of the "rich" to the extreme (taxation in excess of 70%) seems counter-intuitive. It makes no sense.
I don't know your friend, I know little about Carson; but it seems more plausible to me that Carson made the statement in an off-hand manner, with no real intention of moving anywhere. Like how I and my wife talk about moving to Hawaii and living out of a tent on the beach.