Games are just games, they don't have to mean the same thing to everyone. The way you view them tells more about youself than about the games.
Am I playing chess because I love chess? To have fun? In that case, cheating is counter to my goals (unless I enjoy the act of cheating itelf, but that's getting besides the point).
On the other hand, is chess simply a means to an end? Am I playing chess because I want to win something? If so, cheating is but one of many possible decisions I can undertake to increase my odds of winning.
Where professional games are concerned, where money and fame are at stake if you lose, cheating is downright inevitable and certainly not something to be surprised about.
I am implying that because that's inevitable in a situation where winning is so much more important than simply playing. Again, these aren't games of pleasure, games "for fun". These are games with valuable stakes on the table.
Even Magnus himself can be argued as playing to win in order to eventually obtain the famed 2800 ELO or whatever the magic threshold number is. If evidence comes out that Magnus cheats, it would be a shame but I wouldn't be surprised either.
In situations where the ends justify the means, the means will include cheating.