>paying what in retrospect will have been an excessive price

This can be said about any negative price movement. You still get the same amount of oil you agreed to regardless of if the price goes up or down afterwards.

So if this sort of "insider trading" is bad, what does this mean for other sorts off strategies hedge funds do to get an edge, like flying helicopters to look at how full oil storage tanks are? Should that be banned too? The article basically argues that any sort of alpha is bad because it disincentivizes others from participating.