Your position was entirely clear. What you failed to explain is why the pollsters want to show Trump in the lead. Why not Rubio?
Trump is perceived as the best chance for Hillary and there is no doubt all his attention has gained enough support that polling republicans would give Trump an advantage, especially is they were tea party republicans.
Why not put Carson in the lead for that matter if they polls are rigged, would be your next question? The results they end up with have to be within reason given the people they are calling. With the lack of attention Carson is getting, calling even tea party republicans would not garner enough support to put Carson ahead of Trump.
So yes the polls have to be within reason, but are not a true reading of what is really happening. Who they are calling is the determining factor.