I don't think this is a well written article, but

Is it because they are only somewhat more right than wrong, but they do beat random guesses?

is not right. OP might ignore them because his knowledge screens all the information in their opinions. For example, that might be true if he had studied relevant topics and was already an expert in Industrial Organization.

I think the OP's point would be better said as something like "you should only update your probabilities when a person's opinion gives additional information rather than when they are an expert."