"Bugmaster advocates banning consumption of meat", most people would probably just shrug. But if you said "Reverend Bugmaster advocates banning consumption of meat", people would sit up and take notice.

I'm pretty sure these two statements would have exactly the same effect on me...i.e. proportional to how much other information I know about you and how many reasons I already have to respect your expert opinion. I do have a lot of reasons to respect Dawkins' statements on a lot of things. He knows more about biology than I do, and so if he says something about biology or evolution, I'm prepared to take it at face value. I don't think he's studied religion in depth, though, or really undergone a non-biased process of weighing its pros and cons. I have no reason to conclude that his religion arguments are more valid just because he's a good biologist.