I’m not convinced that Comey would do this if HUMA were in jeopardy.
It would have to be info that had Clinton in jeopardy.
That will be the only justification.
If not evil, he might use incriminating evidence against Huma as a way of bringing the story back into the news and bringing Hillary!® down. If evil, he's acting on direction from higher up, or trying to salvage the best he can of a bad situation for his masters.