To paraphrase SE Cupp from today's oped, the GOP just killed one of the arguments made by Rand Paul and some others who have leveled the charge, "Trump isn't a real Republican". Ummm, lol... I guess he is now, since they made him sign his "I R teh Republican" pledge.
Kinda defeats that charge, while totally legitimizing his campaign as a serious candidate.
And since he kicks all their azzes at social media, expect him to turn this into "Why The Donald made the RNC his beotch by making them admit he's the alpha candidate who they know would wreck the GOP in the election based on his pure awesomeness and galactic levels of win."
Give it less than 48 hours, and Preibus is Trump's ho.