No article link, but here's one: https://www.washingtonpost.com...
Even if it's possible there's something to the lawsuit, the first two lawsuits were clearly absurd. The first one claimed there's no tuna whatsoever in the tuna, which is not only something that's impossible to get away with, but they refused to release the lab tests.
In the second lawsuit, they claimed it "was not 100 percent sustainably caught skipjack and yellowfin tuna" which is curiously specific wording. Are they really claiming that sustainable tuna have different DNA from unsustainable ones? And does that mean that they suddenly admit that the lab tests do show tuna when they claimed they didn't the first time? They didn't release the lab tests for this one either.
At this point, I'd assume either 1) they're suing only for the publicity and don't believe anything's wrong, or 2) they're fanatics who don't understand that no evidence means no evidence. It's possible that they have evidence the third time, but I wouldn't bet on it.