Russkies want Hillary in the WH. So why release them?
That's my take as well. Only if Trump represents a business arrangement that personally works for Putin would he be a better President for the Russians and even at that, with such a business arrangement comes the specter of a resurgent America.
Having Her Heinous as President, however, Putin knows there's no resurgent America because even if he burns her emails, she'll continue dismantling what Barry didn't get to. In the meantime, while she's doing that of her own accord, Putin can blackmail her every day of the week for whatever else he wants.