It still needs an 'S' or and 'ed' on Dumb, it's a question of whether the article is talking about how this movie was dumbed down or how he continues to dumb down the franchise. Either way, it needs to be 'How JJ Abrams dumbed down Star Trek,' or 'How JJ Abrams dumbs down Star Trek.' In the second case it would make more sense if it was like a headline, a la 'Tigers win (not won) the world series', hence 'JJ Abrams dumbs down Star Trek!'