The Social Democrats haven't won the presidency in decades and their current candidate sunk them in this election process even though he was sure to win, but some missteps he took associating himself with people connected to a huge real estate scam sunk his campaign.
Whether this move helps Social Democrats (PSD) is unlikely, as their current candidate is still just as unpopular and would most likely not win.
You are correct that because of this Russophile candidate the runoff turned into a pro-EU vs pro-Russia fight.