Is there a link? "Possibly" is about all you can say.
There's no doubt that you can process even the best foods and make them unhealthy. I am always wary of that whenever I read another study. This one is interesting because it tries to summarize a lot of studies. By its own admission, some studies show a link, others don't.
I've seen this scribbed in several places - even some magazines. I always read it, but am never satisfied with the "conclusions".
One of the first suspicions I have in relation to the link with flax seeds is whether they used seeds that were treated with pesticides (which ones; how much, etc.). There's the first wild-card that most studies seem to ignore.
Another thought is that flax seeds are actually hard to break-down if chewed as seeds (most just come out the other end "untouched"). We can fix that on an industrial scale by processing them (grinding them up). In any studies involving flax - who processed the seeds? How careful are they with the product? (Flax oil will rapidly oxidize, and oxidized oil is very toxic - carcinogenic - a good reason to NOT buy flax oil, in my opinion). These are some of the major questions that always go unanswered in these types of publications - a bit like the latest on Vitamin E.
Until there's a reliable source of date, from which true conclusions can be drawn, this comes down to a judgement call only on our parts.
I personally will continue to use flax seed and other sources of LNA. I grind my own organic flax seeds, and I use them immediately to minimize oxidation. Will I die of prostate cancer? I hope not, but I guess someone can email me when I'm dead so I can tell you what killed me...