In general, U.S. Soccer coaches have a rule about calling in overseas players - they don't do it unless they're going to play them. Honestly, why subject someone to the travel if they're not going to step on the field?
However, over in Colorado, they're apparently worried that Beckham will miss the opener there. Yet at the same time, they question whether Becks will even get a cap.
First of all, three days rest is much more what Beckham got last year when he played the entire match for England versus Germany before flying back to an MLS match versus Chivas USA the next day. Secondly, if he only plays part of the match or not at all, why wouldn't he be fine to play in Colorado? Finally, perhaps MLS learned about marketing matches, any matches, as "Come see a certain someone" because players do get injured and that's just part of the game.
Maybe they're actually marketing this as "Come see the Galaxy" and if people haven't figured out that David Beckham is a member of that team, well, they're probably too far out of the soccer loop to be converted into fans anyway.
Beckham will likely play, barring injury, in both games - the one in France and the one in Colorado.