Not to mention the Ukrainians themselves.
I think people sometimes underestimate Ukrainianness, but if the Poles are planning to keep the lands of right-bank Ukraine in the hands of the Polish landholding class, they're going to be about as popular with the peasants as Skoropadskiy, true.
The heart of it is that the Ukrainian peasants didn't care about national questions one way or the other but did care a great deal about land questions. So a lot depends on what sort of regime there is in Russia, eventually.
An ASB polish victory creating an ukrainian republic allied with Poland means that every russian regime : monarchist, republican, nationalist, or communist, will try to crush this ukrainian republic in the 20's or the 30's...
That's a simplification. Suppose a lefty republic eventually came about in Russia? Now Poland's problem is more that Russia looks a lot more attractive to large sections of Ukrainian society than any Ukraine which leaves Polish and other landlords in possession of their estates.
And Poland did not prove outstanding at winning over educated Ukrainian sentiment, to bowdlerise considerably.