The summary's statement that the researchers have "identified" perforins as the causative agent of cell membrane perforation is misleading, that has been known for quite some time, as you mention.
You are quite right. Perhaps the sentence would have been more accurately phrased as the researchers having identified the mechanism of how perforin works. I don't have any experience in this field and this is a mistake on my part. Rest assured that this mis-statement is unintentional and I hope my future submissions will be of higher quality.