You could say anything you wanted to someone you thought you were never going to see again.
That's why when major badasses greet each other in movies, they don't say anything, they just nod. The nod means, 'I' am a badass, and I recognize that you, too, are a badass,' but they don't say anything because they're Wolverine and Magneto and it would mess up their vibe to explain.
He's got a great sense of humor for a guy who never says anything.