One must always be open to the possibility of something that can't as of yet be proven, BUT a healthy scepticisim is a good thing.
One should always understand the history behind soemthing like "chi" before it is discounted.
But I agree that anyone trying to pass off Chi as some "mystic mumble-jumbo" should be ignored.
In terms of physical actives and prowess, almost everything we do can be explained by biomechiancs and physics ( as it relates to the human body), so there is no need for speaking of "chi".