lmao his promise isn't worth the paper and printer ink his john hancock sized signature was written on. If he wanted to, he could easily turn this into a positive for himself in the case that he doesn't win the nomination by going on about how the RNC begged him to sign due to the lack of confidence in the eventual nominee being able to beat an independent trump, and that it was a "good business decision" to give the establishment an empty promise that would benefit him in the long run. His base would eat that pseudo-savvy mentality up.