I don't think that's a poll you can read too much into. It's pretty obvious that if you're a strong supporter of one candidate and a pollster asked you if you wanted to see their rival drop out, you'd say yes.
Not only that, but you've also got to consider that the average voter knows next to nothing about how many primaries are left, the current delegate spread between Clinton and Obama, how the superdelegates work, etc. But those are the things that determine how much of a chance each candidate has, which in turn determines whether or not they "should" drop out. So basically, this is a poll question that asks people to offer an opinion on something that most of them are fairly clueless about.
