Implausible for a number of factors.
The biggest factor, in my opinion, is that pagans in Eastern Europe didn't convert to random religions on a whim or because of their heart's desire, but only if converting to a religion would give them or their nation an advantage. Christianity gave pagan rulers an advantage: it opened up trade and relations with their neighbours, it encourages the spread of technology and innovation from their Christian neighbours (which were almost always more advanced than the fresh converts themselves, for obvious reasons), and it also allowed ambitious rulers to go on conquest sprees in the name of Christianity, and, in something that a lot of people forget, becoming Christian (at least Catholic) allows you to advance in the title pyramid and become a king, Islam does not.
Islam would be a detriment to any Eastern European nation which adopts it: it would immediately be hostile to nearby Christian rulers, it would be very distant from any Muslim nations worth a damn, so no trade or innovation spread, and while I suppose it would still enable an ambitious ruler to use his religion as reasoning for conquering neighbours, it doesn't enable the royal title (I mean, you can still claim you are a King or equivalent, which is what the Lithuanians were doing until the Union of Krewo, but nobody will recognize you as one).
As such, no EE pagans adopted Islam. It's quite simple, really.