The Uranium associated investigations under Obama's DOJ were dead for 1.5 of those years he was awaiting sentencing. So I don't think that Condrey cooperating with the feds is the reason unless it is to help cover things up.
Beyond that, it's more likely that acting AG Rosenstein knows more about the government side of the associated Uranium scandals than does Condrey. Beyond even that, if Condrey actually did know things about the government side of the associated Uranium scandals, he would actually be putting Rosenstein, his buddy Mueller and all of their cohorts, Holder, Hillary, Obama... in jeopardy.
Condrey’s knowledge of the criminal conduct of the individuals you mention may be why the Obama DOJ hadn’t had him sentenced, yet. On the other hand, his prosecution could not be controlled by the DOJ once the local US Attorney got it rolling.