Is this supposed to be a coherent explanation or am I missing the point?
She's saying that it doesn't make any sense for people to be calling for her to drop out, because past primary battles have gone into June, so it's not really that late.
But of course, the double meaning that some people might take from this is that she's implying that the nomination isn't really decided because you could still have some dramatic event like the RFK assassination.....which is obviously kind of offensive if that's what she meant, since it would be like saying "Well, Obama could still be assassinated, in which case I could win."