When you're rising, like Kovalev is, it's only logical to not duck a fight to be recognized. Once he hits the top level and scores even bigger wins than the one against Hopkins, even he will have his share of "he's ducking <insert random name here>" by idiots.
Who is there for Kovalev to duck? Who's more dangerous than he is? No one would qualify as "duck-worthy" in his division except for him.