It is as valid to state that attendance in public school causes students to shoot their classmates, as to ascribe that behavior to playing a game. In the 80s and 90s, freedom of expression triumphed over attempts to eliminate pornography. It was a heated and prolonged battle during which radical feminists joined with the religious right to call for censorship. They lost largely because their data was widely discredited. I do not believe the censors will lose the fight against violent video games however flawed their evidence may be.
People are in a panic over violence in the schools and the government needs a scapegoat.
It cannot blame the public school system for which it is responsible. It cannot control or repair the break down of the nuclear family that has left millions of children without the traditional safety net of values and guidance. And it can control retailers like Wal-Mart through letters of intimidation signed by Senators. In the final analysis, it probably will not matter how weak the common sense or how anecdotal the evidence is that underlies their arguments. The censors will probably win.