I wouldn't go so far as calling this fraud, as the OP didn't get any extra miles, just redirected them. But that's a fine line. Perhaps the OP could have called NW and just admitted the truth? Would they have fixed it? I guess we'll never know.

However, I do see this as emblematic of a major societal issue. People don't take responsibility for their own actions and mistakes, and won't accept the consequences of such actions. I see this very much like people who back up on the freeway when they miss their exit instead of just going to the next one. Or book a flight on the wrong date and blame it on the web site when they know full well it was their own mistake. If they would just accept the consequences of their mistake and move on, everyone would be better off.