In a way you have a point although Comey appears to be a dirty cop. If Comey had charged her, she might have been forced to drop out and likely replaced by Bernie Sanders - and he might have been more difficult to defeat.
I am of the opinion Bernie would have won.
The emails of confidential info are even close to Comey’s first time letting the Clintoons legally slide. Goes back to Whitewater I believe. Comey has been facilitating the skating form of the Clintoons. He can’t work total miracles though.