Interesting. I definitely agree with your statement about causation (cancer causation is a highly difficult topic), but I would put stock into this finding. I work for a leading cancer center in New York City as a research study assistant and I can tell you our studies have some extremely interesting results regarding diet. Of course, I work with patients who have prostate, bladder, and kidney cancer which this article clearly isn't targeting.
I think the take home message is to do everything in moderation, including moderation itself. Those top 20% of red meat eaters probably were stuffing down more meat in day than we do in a week.
-HL