"They have a strong viewpoint" is a not the same thing as "obviously biased." Conflating them is a rhetorical sleight of hand.

When I go to that page, I get a few grafs on recent mass shootings (which, barring conspiracy theories, everybody is presumably on board with having happened). Mentioning those at all indicates that they have a viewpoint, but I don't see anything that indicates that it biases their transparency work. There's nothing to justify the insinuation.