Gotta love George Carlin's take on this:

Muhammad Ali's back at work again; he's being allowed to work once again, Muhammad Ali. He wasn't for awhile, as you know. For about three and a half years, they didn't let him work. 'Course he had an unusual job, beating people up. It's a strange calling, y'know? But it's one you're entitled to. Government didn't see it that way. Government wanted him to change jobs. Government wanted him to kill people. He said, "No, that's where I draw the line. I'll beat 'em up, but I don't wanna kill 'em." And the government said, "Well, if you won't kill 'em, we won't let you beat 'em up! Ah, ha, ha, ha."