Why did you remove the review? Just to spare his feelings? I wouldn't have done that! If you've written an honest appraisal of his site, however damning that may be, you shouldn't bow to being blackmailed by him.
Doesn't google do anything about clickbombers? It's not fair for someone to lose their adsense because of another person's actions. Google knows about clickbombing and shouldn't punish the innocent party. So he clickbombs you, you remove your review of his website, and you may possibly still get banned...isn't that like rewarding a kid for misbehaving? If he has adsense too he should realize that you could also clickbomb him and get him banned. I just wish google would do something about clickbombers. Maybe they will one day.
banning his ip wont make a difference he can just click bomb through proxies... Just tell adsense to clear it up.. send them the ips used etc. Then find out who he is through whois or something and ask a lawyer to ring his phone or something intimidating
Block his IP that's the best way to do it but if it's a dynamic IP address he can just restart his router and continue to clickbomb.
remove the ads..and then mail to google.. im sure while removing ads for some days ... will protect ur account..