Similar to the discussion that happened in Arizona over renaming Squaw Peak. Just because its part of history, it doesn’t automatically mean it should be kept. Just because squaw was at point or another meant “girl” doesn’t mean it was not later used as a derogatory term for Native Americans.
That guy needs to understand that it has nothing to do with political correctness but that the product he is selling is reflective of a time where people thought shit like that was acceptable. Understanding history is one thing, selling the bullshit and marketing it as “lol history” doesn’t do anything to help understand the context of the items hence he is just being an asshole.