They are both electronic cash systems that use two fundamentally different approaches. If someone took over 51% of the hashrate then that's someone hijacking the network. If you fork off of it, it becomes a separate currency based on the concept of Bitcoin. I am also very weary of Roger Ver, so we can't take his word for gospel just like we can't take Adam backs or Jameson Lopps word.
Also there is no one true "Bitcoin" there are different types of currencies built upon the concept of Bitcoin.