Sorry, I'm afraid I don't quite get what this saying means. Is it saying that those who are attacked should not speak up or try to defend themselves? That would seem awfully convenient for those who like to "toss sticks", wouldn't it?
Some people say they would have "laughed it off" themselves. However, it frankly comes across as a bit strange to translate this to a notion that others (or namely in this case, Plushenko) "should" react the same way. As we've seen, in Russia (as in most countries), the need for legal recourse against defamation is recognized. To "laugh it off" is one way of dealing with it, to seek such a legal recourse is another way: I don't see how the former is more of a "high road" than the latter in any morally meaningful way.
Specific to this particular situation, one thing to mention is that over the years, the Russian tabloids have invented many false rumors about Plushenko, and he has for the most part (with exceptions) forborne from reacting openly. But this time, Zhurankov is not some tabloid reporter. He was on Eurosport, a serious television sports channel, commentating on the 4CC, a major international competition. He was speaking from a position that would generally be considered a position of authority on figure skating. And he was not merely making a factual mistake in the course of commentating: he deliberately brought up Plushenko's name in a situation where one would not expect it to naturally arise (given that there were no Russian skaters in the competition). He was not merely speculating based on a lack of knowledge: he specifically mentioned the Channel 1 video news report of Plushenko in the Israeli hospital, which shows that he was fully aware of the facts of the situation. Later, he admitted directly that he was trying deliberately to "bait" Plushenko.
To say that Plushenko's injury and/or operation were not legitimate is to impugn his honesty (as well as the honesty of his team, his doctors, and Channel 1). As Plushenko himself has said more than once, to be called a "liar" is what offends him deeply. Perhaps to some posters here, such matters of personal integrity would only elicit a reaction of "who cares?", but by all indications, it is in fact something that is important to Plushenko. Given this, it seems to me to be a quite natural and honorable (yes, Plushenko is one of those people who still use the word "honor" in this day and age, so I will use it here as well) reaction to try to seek redress, whatever the outcome.