False hope, cunning on Michael's part, that's how.

"Come on. Don't be afraid, Carlo -- Come on, you think I'd make my sister a widow? I'm Godfather to your son, Carlo --No -- Carlo -- you're out of the Family business, that's your punishment. You're finished. I'm putting you on a plane to Vegas -- "
And he even goes as far as presenting a plane ticket to him.

Cool, cunning and calculative Michael at his best.

.