Besides, what has Europe done so far for Ukraine, apart from sanctioning Russia, harming its own economy collaterally?
First of all Greece is a sovereign nation and it can do business with anyone it thinks appropriate. I can't recall any of Greece's European partners, from East or West, siding or supporting Greece on its national issues such as the Cyprus problem, the FYROM issue or Turkey.
Secondly, the probability of Greece re-positioning itself closer to Russia is practically zero, as long as Greece remains a full member of European institutions and NATO (The Guardian). It is thus unlikely that Russia will proceed towards a closer relationship with a US ally.
It is up to the EU to gain the hearts of the ordinary Greeks again, by showing a bit of tolerance and compromise. Not for the sake of Syriza, but for Greece's citizens, the unity of the EU and the euro. If the Greeks see some relief and an end to the constant humiliation, they may gladly return to the established, mainstream political parties.