No doubt. I'm sure it was. I just think it was also a genuinely useful indicator of exactly which reporters aren't/ don't have access to people with general knowledge of the subject and that more people should make jokes like it for that reason.
(Actually, a good test for whether someone has A-lister perception is to see if they can see past their own prejudices.)
Because, in your words, someone should know on the face of it, that "seven proxies" is implausible? Please explain how I should know that. Would it be worse or better if it were 6 or 8? Please answer from first principles concerning network technology. (The fact that you are not accounting for the fact that there are multiple interpretations to the term "proxy" makes my eyebrows raise.)