I'm pretty sure curtailment is the exact reverse of what the comment you're replying to is talking about - it happens when there's an excess burst of wind power compared to demand, whereas the question is about wind power filling bursts of demand. Since there's almost no curtailment it seems pretty clear that wind power doesn't currently play a role in filling those; there's just not the excess capacity for it. Of course, curtailment is only low right now because most of the generation is from fossil fuel plants which are shut down in preference to wind. Once that changes curtailment will go up and capacity factor will go down.