It is CBI Ron for a lot of reasons already stated by others.   "But wait" you say... "'CBI Ron' is not on the list." 

However, a "Brett Styles" Jr. using the Alias "Ron" might be.  

I think that will be the twist and how the producers can openly say Red John is on the list BUT still have a surprise with someone who doesn't seem to be on the list but ~technically~ is.

So Ron is Red John
Ron's real name is "Brett Styles Jr"
Brett Styles is on the list.