Rest in peace?!? Isn’t there something about a millstone about one’s neck if he should lead the flock astray? Isn’t that more of what he did?
The millstone was for causing an innocent child to sin. At any rate, it's bad form to spit upon the dead no matter how many Bible verses one misunderstands.
Matthew 18:
The Greatest in the Kingdom of Heaven
1At that time the disciples came to Jesus and asked, “Who, then, is the greatest in the kingdom of heaven?”
2He called a little child to him, and placed the child among them. 3And he said: “Truly I tell you, unless you change and become like little children, you will never enter the kingdom of heaven. 4Therefore, whoever takes the lowly position of this child is the greatest in the kingdom of heaven. 5And whoever welcomes one such child in my name welcomes me.
Causing to Stumble
6“If anyone causes one of these little ones—those who believe in me—to stumble, it would be better for them to have a large millstone hung around their neck and to be drowned in the depths of the sea.
7Woe to the world because of the things that cause people to stumble! Such things must come, but woe to the person through whom they come!
8If your hand or your foot causes you to stumble, cut it off and throw it away. It is better for you to enter life maimed or crippled than to have two hands or two feet and be thrown into eternal fire.
9And if your eye causes you to stumble, gouge it out and throw it away. It is better for you to enter life with one eye than to have two eyes and be thrown into the fire of hell.