He's a good player, no doubt, but he's never even been an all-star. Look at this quote on the seven original players still on the team. There's a long list of impressive accomplishments for all the players, except for Bibby all it says is that he's ranked in the top 25 in a few statistical categories:
The five players named today join the seven core group players previously named to the USA team which includes two-time Olympic gold medalist and 19-year NBA star Karl Malone; NBA All-Star and 2000 Olympic gold medalist Jason Kidd; Tim Duncan, the NBA's 2002 and 2003 Most Valuable Player; Allen Iverson, a perennial All-Star and the NBA's 2001 MVP; Jermaine O'Neal, a 2002, 2003 and 2004 NBA All-Star; Tracy McGrady, the NBA's scoring champion in 2002-03 and 2003-04, and Mike Bibby, who wrapped up the 2003-04 regular season as the NBA's lone player ranked among the top 25 statistical leaders in points, assists, steals and 3-point shooting percentage.
http://www.nba.com/knicks/news/marbury_usa_040514.html