First of all there is no mention of Kerala in this article and you forgot the main sentence in this article "The Maoists have become squeezed in their traditional central states.".
The BBC report was not in response to the Kerala claim, this was in response to the huge presence of Maoists in India.
These are the reports that Maoists in Kerala are getting trained in Jharkhand:
Kerala Maoists get training in Jharkhand - Times Of India
I am not making hollow claims, I know what I'm talking about, I've done extensive in depth research on this topic, & many members here know it.
So according to you , if a Maoist walks through my district it will come under Maoist affected.
There is a difference between being affected/having a presence, & operating from a district.