The most plausible explanation as to why Comey reopened the investigation was not to derail her campaign, but to absolve her after she won. They never though she would lose. Comey was confident that showing this before the election would defuse any doubt that she was duly elected. Gowdy's comment, to me, is saying that people will look back and say "thank God for Comey". Not for doing his intended purpose but for blind luck in derailing her presidential bid. He's dirty as shit.