In this Ninja message board thread BlkSabb quickly posted these links (here and here) to some interesting posts on another board from someone who played Garry Kasparov in his Belzberg simul in Chicago last week. At least the guy was supposed to play Kasparov. It turned out his rating was too high for the event but this wasn't noticed by Kasparov until the game was underway. (The other links go to a fun story of how Kasparov made it up to the guy.) There is a 2000 rating cut-off for most of Kasparov's promotional simultaneous exhibitions, something that surprises many people.
This is discussed in more detail in the thread at the first link above, but the bottom line is that these are promotional events and the organizers are on a tight time schedule. The Belzberg simul at the Stock Exchange here in NY earlier this year included dinner and drinks and had to be wrapped up on time.
This is not serious chess and the addition of just one or two strong players can slow things down dramatically. When time isn't such a factor and the players are there just for the chess (at clubs and against juniors, etc.) I've seen many large Kasparov simuls with players rated over 2300 FIDE.
I suppose that Kasparov could simply try to play faster regardless of the strength of the players. He would lose and draw more games, something he despises even in simuls. Some of the great simul players of the past didn't mind losing so much and played more to the gallery. Alekhine would experiment with wild gambits and unsound defenses, Capablanca played with unbelievable speed against everyone.
Kasparov doesn't want to have fun in these events. He plays conservatively and classically and feels that he should have a shot at a perfect score each time out in the time allotted. He believes that's what the sponsors (and players) want from the world #1. This is probably true in these promotional simuls. No one there would appreciate that he played a few spectacular games (most players don't even keep score) They would only understand the final score. Of course WE prefer a few brilliancies to a 20-0 score, so it's really a greater loss to chess. To have that shot at 100% in a two-hour exhibition (or any fixed, short, amount of time) some rating limit is required.
I think this is more of an example of how Kasparov sees his role and image as standard bearer than anything else. He believes losing is simply not acceptable and that others feel the same. Is it too late for him to change?