The study's findings aren't surprising. We're a group species and we desperately want to conform to the norms of whatever group(s) with which we most closely identify. At the same time, we want to believe we are acting in a good way. Thus we seek to virtue-signal to our peers (in this case by retweeting obviously false information) while simultaneously ignoring the disconnect between reality and desire.

Few if any humans have ever sat scheming in a Bond-style lair, consumed Iago-like with an awareness of their ill intent. Nearly all the horrors of humanity have been perpetrated by people who were convinced of their own righteousness.

In other words, what people think about themselves is no guide whatsoever to their actual behavior. I would bet that even the effect mentioned in the article (get people to focus on evaluation of credibility prior to retweeting) would attenuate rapidly in a real-world situation. People will always sacrifice reality to belief in order to avoid potential censure from their group.