Quiz

But what did he violate, what is he being punished for? Copyright, perhaps? Well, he didn't cite Yezhov, so what's the big deal?

Is this your final answer? ))
Okay, actually, I don't see the point in dragging it out; it probably wasn't the best question I formulated. Uranium is almost right in this sentence:

Another option is that Yezhov was no longer the People's Commissar, so they called in a new one to express their gratitude.

The point is not about gratitude. The key question is: why was he called in at all? Because he removed Yezhov's name; Yezhov had indeed retired... But practically no one outside the relevant organization knew about it yet. So, Ozhegov was called to the authorities to inquire about how this happened... And not because of a copyright violation, as one might think.
However, it might just be a tall tale. But... I think Uranium almost answered the question.