Does it seem odd that atheist Steve Irwin would not be in heaven, but born again Jeffrey Dahmer would be?

No, it doesn't seem odd, if you read the bible and believe what Jesus tells us. Anyone can receive forgiveness, if they repent of their sins and put their faith in Jesus, that His death and resurrection was sufficient to pay the penalty for our sins. It doesn't matter how "good" we are; what matters is whether or not our sins have been washed clean by the blood of Christ. If Steve Irwin never repented, then he is in hell. And I guarantee he would not want anyone reading this to join him there. And if Jeffrey Dahmer truly repented, then praise God, another sinner saved!