The author argues that it would be okay to object to what Warhol has done if it were already well established that what he did was a violation of fair use, but

The author argues that it would be okay to object to what Warhol has done if it were already well established that what he did was a violation of fair use, but that it can't already be considered well established because otherwise there wouldn't be a lawsuit about it. But there are plenty of instances where clearly established precedents nevertheless require lawsuits for their enforcement.