Why was Platkin recused from the case?
Before he became AG, he was consulted about maybe joining the Eisemann defense team in some capacity. It didn't pan out, but it was enough for him to recuse himself as having had some prior connection to the case.
But don't forget, recusing oneself maybe blocks him from making decisions about the case, but it does not absolve him from cleaning out corruption from his office, regardless of the case. I don't think he can just wash his hands from this whole vendetta.