I don't see what the one has to do with the other. If we all waited until we were perfect to have an opinion about anything, we would never open our mouths. The fact is that Plushenko has a far less stable chronic injury than most other skaters, and it's natural to feel concern for him whether one has a bad lifestyle oneself or not. It would be less humane to say, "I don't care what Plushenko does to himself because I'm much more worried about my own health. As soon as I give up sugar/liquor/tobacco, I'll start caring about other people. And since I'll never give up sugar/liquor/tobacco, I'll never care about anyone else." That approach doesn't really work for me.
(By the way, I don't drink or smoke or overeat, so maybe I can be permitted to express worry about a skater I admire.)
But he needs to live the life as he wants to, not as some people are telling him to do. If he wants to skate, let him skate. If he wants to compete, as long as he is good enough to be sent by his Federation, he should compete. Is it healthy? probably not, but elite skating as such is not very healthy anyway. The amount of injuries every year...but that's life. That's the unfortunate part that comes with most of elite level sports.
Look I am not saying that people should not be expressing their worry, but what I am reading on the forum goes a bit further than just expressing worry. I think that anyone who does not live the perfect super healthy lifestyle should not criticise someone else for doing something unhealthy. The pot calling the kettle black...