I think you'll find that "professional" herpetologists probably wouldn't refer to their (P.m."pimbura"
vernacular name at all, when in certain circles. However, when talking on forums such as these, yes they probably would use "common names." [Just to make a note, this subspecies is no longer recognized by certain groups (such as CITES anyway)]
As someone that holds a PhD in herpetology, I think I am included in your group of "professionals." I often have a gripe with "common" names, and the way they lead the "amateur" to believe that a certain species / subspecies only occurs in a certain country / area. Take the "Brazilian" rainbow boa for example. Of course, it only occurs in Brazil.....uh-hum!
However....in this case....seriously, get off the guy's back. Ceylonese / Sri Lankan Python.......there really are better things to discuss! Pedantic isn't the word!.....