I think it was something in the water in Nam that drives him to this.
No, it's simpler than that.
McCain is a crook and he proved it with his role in the "Keating Five". "Campaign reform" for McCain is just his cheap, misguided way of trying to "make amends" and prove to himself and to the world that he's really not a crook. Yet his idea of "reform" always translates into, "Stop me before somebody comes along with a pot of money and corrupts me again!"
In McCain's world, ALL politicians are inevitably corrupted by campaign money because they are powerless to resist. You know - - because they're all crooks.
Like him.