Horowitz does not have subpoena authority and can only force interviews with current federal employees. It’s possible Rosenstein turns out to be a “good guy”. We’ll see ...
We'll see?
He's part of the Uranium One coverup, he's part of Mueller's witch hunt, he signed a FISA warrant, he stonewalled on releasing documents, he threatened Jim Jordan's staff, he's (possibly) tried to use the 25th amendment against Trump and is now he's out the door.
It's pretty evident he's not a good guy.