I firmly believe that this post regarding SpaceX and their rocket landing using mechanical arms is true, as it was previously reported numerous times by the New York Times and Washington post.
This being said, I do find this post to be slightly factitious as in your title "one step that brings humanity closer to mars". Due to the lack of evidence provided in the New York Times article, they don't actually describe the relationship between the two events. Furthermore, the article suggests that SpaceX has a lot more challenges to face the distance between putting us on the moon or mars. Although SpaceX is able to land this rocket with the use of mechanical arms, it's evident that the SpaceX launch event wasn't a definitive advancement for us to be on Mars. Due to this, this claim is Exaggerated/