Was this proofreader assuming the role of Chief of the PC Police by making such an ordeal over the term "salesman" vs. "salesperson"?
In my opinion, yes. This is absolutely ridiculous and if the person that gave you a hard time over that could actually step back and look at their reaction, they would be embarrassed.
It's funny how the politically correct tend to determine that most things should just be different from what they were - it shows that they don't posses critical thinking skills. For example, many years ago, we would call a female actor and "actress" and a female waiter a "waitress", a female flight attendant a "stewardess". However, the terms have fallen out of favor. They are not politically correct because they designate gender. I know not everyone does this yet, but eventually they will - I call male and female actors "actors", "stewardesses" are now flight attendants, waitresses are now waiters. After all, it's wrong to distinguish between male and female.
Oh wait... that's not true. It's only wrong to use gender specific words if we didn't use them before - and if the original word happens to include man.
"Salespersonship"? Really? I suppose we could simply neuter every word in the english language. It would be in stark contrast to other Latin languages in which every noun is either feminine or masculine and adjectives are changed to match the gender of the noun/person to which they refer. And in most cases these nouns are truly gender neutral... they even have words with "feminine endings" that are "grammatically masculine" and vice versa! "el problema" and "la foto", for example. Wait - does that mean that men have more problems and most pictures are of women? No. As far as I know it means nothing at all. Imagine people that don't speak English as a native language. Not only must this be difficult for them to practice, but even to comprehend!
You will find plenty of people that will say that I am a hateful person because of this, but there is nothing grammatically incorrect about using the word salesman! This proofreader is imposing their own personal philosophies on your writing. I would consider that a breach of their fiduciary responsibility as a proofreader or proofreaderess, and declare them to be incompetent to hold that position.
Do people in this modern age (post the original PC revolution that came to a head years ago) still generally take offense to the word "salesman" when it is possible for someone in sales to be a female, therefore any reference to gender associated to occupation is offensive and wrong?
Yes. They consider anything wrong that is either distinguishes gender, but also anything that is non-gender-specific. Basically everything. It gives them purpose. It is their identity. Was your writing SO good that the proofreader or proofreaderess had to resort to the use of "salesman" to feel that they had some value? That says a lot about you and something about the self esteem of the proofreader/proofreaderess. Again, if they were to step back and look at this objectively, they would notice that it is NOT you who is making the distinction - it is them. The proofreader/proofreaderess or "proofperson"is projecting their insecurities onto your writing. Did you mean to be a biggot when you wrote the word "salesman"? It certainly doesn't sound like it. So in whos sick mind did it become something bad? In the mind of the proofperson.
And if so, would not this apply to any occupational term ending with "man", e.g. "journeyperson" vs. "journeyman" or "landperson" vs. "landman", therefore never end a occupational name with "man" because that would offend most people?
Yes and no. Yes, it will offend many people. But no, we shouldn't stop using the words with "man" in them. What about a "manhole" cover? Should we call it a "personhole cover"? A manhole is named a manhole because men go in it to work. Sure, some women do, too... but I'll bet those woman are fine calling it a manhole - maybe there are a few that hate the name but still use it. Why? Because we all compromise to fit into society in some way. And forcing us to become less able to do that certainly doesn't help us in the big picture - as a species. We've evolved over many years to have these qualities that allow us to blend socially. It is only because of the freakish minority who consciously choose to stand in judgement of people for something as malleable as words, that we are forced to suppress it. I don't believe in doing that and I don't. I may lose some things because of it - in fact, people at work these days are often shocked by any type of candor. It's ironic, since they are the same people that want to post their innermost thoughts on Facebook. But in person - it's not important what is in your head or your heart - only what is on your lips. A person could hate women... treat women like garbage... but call them a "salesperson" and they guy is somehow OK? Backwards. Shallow. Naive.
I hope you didn't change the word. The proofperson is wrong.