I think we are taking this the wrong way. The situation is "we more or less blamed Mirai on a State sponsored actor", and we focus our attention on "hey, you were wrong! How dare you suspect foreign governments? That's kind of racist!".

I see it as a minor concern, the major one being "Mirai is the definitive proof that your don't need the means and resources of a big hacking team financed by a government to cripple the internet. 3 kids who want to cheat on minecraft can do it". Sure, we already kinda knew that, but this proof is quite scary.