The light-worker is being roundly castigated by the press because he refused to appear alongside 40 leaders in a meaningless march through Paris. Well enough, but consider; the security services of the United States advise people like him on real and unreal things that concern them about the safety and security of both the country and our royal family. One thing you can bet they told him was that the security services and the Army of France were thoroughly penetrated by muslims and that there was absolutely no way in hell to guarantee the safety of any royals or vice royals sent to march alongside the likes of those that showed up in Paris.
It's also worth considering that the only way the disgraced American Secret Service would tolerate allowing his holiness to attend that rally was if they could flood the city of Paris, secure the entire route which means metal detectors and frisking all million marchers and vetting and locking down every sniper venue along the route.
Not going to happen. Plus, I'm sure that some Jackal close at hand was mentioning the Day of the Jackal plot to his magnificence and suggesting he take the better course of indecision and play golf at Pebble Beach instead.
I'm sure Obama was happy to go along with the suggestion and I'm sure he suggested Biden stand in for him and I'm sure Biden, who gets the same sort of information from our vaunted security services, mentioned that he had a previous tanning salon appointment and must therefore decline the kind offer.