Josh,
Rule No 1: The NASdebate does not always make sense
Rule No 2: The NASdebate is full of statistics, models and analyses (many hidden from prying eyes)
Rule No 3: Statistics, models and analyses don't necessarily make sense
But to put another slant on your confusion ...
Given the traffic figures we have available for Broome, many Controllers ( as well as their Union) believe that C can be performed for basically the same cost as E.
Yes, if you significantly increase the VFR traffic levels, then either more Controller positions or installation of surveillance equipment would be required ... which is an extra cost.
But, as Capn Bloggs points out, if it got to those levels ... E could not possibly be an option ... without significantly increasing the risk to IFR aircraft .
And remember, we are discussing a specific volume of airspace here. Bring another area into the equation and we might have a totally different point of view.... taking into account traffic, facilities, geography, weather, airline movements etc