Yes, I think it would be hugely disorienting in a stage-fright kind of way. Suddenly realizing your words and actions had a much greater impact on the universe than you had ever dreamed.

However I disagree that humans haven't evolved to deal with such a thing. I believe you said elsewhere that as it's currently understood, what humans didn't evolve for is prolonged stress. A viral explosion happens over the course of days or hours. Not quite the immediate fight-or-flight of coming face to face with a bear, but still calling for fast and decisive action.

If his work had never gone viral, he might never have had to face the growing seriousness of the consequences of his actions... or never realized that his voice was being heard.