You’re missing Rush’s point. It’s still a free country and SP is free to do as she chooses, no matter what you try and label her as.
The real point is, Palin is endorsing a RINO as “payback” which of course reduces her “conservative” credibility. Yes, Sarah can do just that for her “free speech”. A principled person would use endorsing McPain, a RINO, as a wise choice in exercising their “free speech”. They'd save that “free speech” for someone who had the same principles. I label Palin what she is ... even if truth and the “label” offend you!