You are utterly missing the point about any lifetime achievement award. These awards were created not just to honor the recipient, but to help advertaise the industry. The first of these types of awards were handed out in the film world when the Academy Awards were in the fledgling years. In much the same manner as actors back then realized there is a direct relationship between stars touring shows and audiences in the provinces being influenced to come see a show in New York, or in movie stars making personal appearances, film actors like Douglas Fairbanks allowed the Academy to give them "lifetime achievement awards" to add lustre in the seasons that had very "inward-looking" nominations. The added presence of the superstars of film bolstered the shows.
Now certainly Hal Prince doesn't need another award, but that is precisely the reason that giving him a lifetime achievement award should include his presence onstage.
Few people outside of New York have ever HEARD of the actors who are going to walk away with the best actor awards tonight, but everyone has heard of Hal Prince. Will people tune in for that? Perhaps. Will they be disappointed if they give the guy a tribute and he's not there, perhaps again. Does it make the theater look silly? You can make up your own minds.
Barring being dead, I can't imagine The Kennedy Center Awards being given to people who don't show up.
Surely they could have checked his availability before announcing the award....
http://www.broadwayworld.com/board/readmessage.cfm?thread=972787#3631451
http://www.broadwayworld.com/board/readmessage.cfm?thread=963561#3533883
http://www.broadwayworld.com/board/readmessage.cfm?thread=955158#3440952
http://www.broadwayworld.com/board/readmessage.cfm?thread=954269#3427915
http://www.broadwayworld.com/board/readmessage.cfm?thread=955012#3441622
http://www.broadwayworld.com/board/readmessage.cfm?thread=954344#3428699