No, just because someone has "the power of mass communication" does not make them one of the most dangerous people in the world. It is the message that is conveyed. For example, let's consider a person who supports abortion rights and another who is opposed to abortion rights. Should that person who is in favor of abortion go around to their neighbors and say, "Ms. Smith is one of the most dangerous people in the world because she opposes abortion!"? Of course not. Just because they have differing opinions does not make them dangerous. Now, this can be taken to the extreme as we saw in the case of Eric Rudolph, a man so vehemently opposed to abortion that he saw it as his duty to plant bombs in abortion clinics and kill the people working there or getting abortions. This is the same attitude that the radical jihadist muslims follow: believe what I believe or I have the right to kill you. Eric Rudolph was certainly a dangerous man because of his actions, not because of what he said or wrote. Even in the case of someone who is anti-Semetic can't be considered dangerous (intolerant maybe, but not dangerous) unless that person acts out in a dangerous way. There is a huge difference between someone who says, "I hate Jews" and a world leader with control of the military who orders the extinction of every Jewish person in Europe, man, woman, and child, by the most vile means imaginable. One is intolerant, the other is dangerous.
If someone disagrees with O'Reilly or any other broadcaster, that person may think they are intolerant, but they cannot consider them dangerous unless they advocate dangerous activities (i.e., KKK advocating lynchings decades ago, Malcolm X advocating violent means to end segregration, etc.)