Why Did Kramnik Really Pull Out of the 2016 King Rex Cup in St. Louis?

Kramnik withdrew from the Cup taking place this week in St. Louis claiming health problems. I'm told by a GM in Europe that he alleged that he had back problems. But......this morning Chessbase reports that he attended an event in the Swiss Alps in which he gave a simul.

Could this really be a case of politics. Note that Rex is close to Gary who ran against Kirsan in the last FIDE presidential election. In relation to the WCC in NYC scheduled for November (still no venue or sponsors announced), we note that Vlad publicly made negative comments blaming Kirsan's sanctions troubles with the US Treasury Dept. on Kasparov.
http://en.chessbase.com/post/kramnik-at-the-verbier-music-festival

                                            Vlad gives a simul in the Swiss Alps yesterday

There are alternative theories that have been presented. US Chess members think it might be easier for Vlad to walk with his back problems than to sit for hours playing in St. Louis. Personally, if it isn't about politics, I think Vlad's French wife brought him some water from Lourdes.  In the best of all possible worlds, anything is possible.