I mean, there's no actual evidence that it was him who edited it, is there? It was just from a firm he used to work for. He's said or done nothing wrong relating to that incident since.
Some people just aren't in politics for all the 'glory'. Look at the shit that gets thrown up on any major player in politics today, their whole lives are splattered over the tabloids - it's comparable to being a leading PL footballer at times. I completely understand why he wouldn't want to become a Labour leader to protect his private life - it doesn't mean that I'm wrong to think he'd still be an outstanding leader if he wanted to be one.