I don't much care for the term "mansplained", but I think it's a stretch to say it's sexist language. It's a simple colloquialism that refers to a well-known phenomenon.
Until they added that line I didn't know the gender of the person writing the article. Explaining something to someone who looks like they don't know something has nothing to do with gender. That they associate it with gender is on their end and shows their bias.
Really funny to see stuff like this on hackers news.
Liberals arts majors appropriate mathematical language in an attempt to appropriate mathematics' reputation. Why is racism "prejudice + power" in this philosophy rather than "prejudice AND power"? It's because liberal art majors know that the lay public is more likely to believe mathematical conclusions than e.g. psychology or sociology or critical race theory conclusions. So they wrap their race theory arguments in mathematical language in order to trade on mathematics' sterling reputation for rigour and correctness.
It's always funny to see things like this on hacker news because well... There are a lot of mathematicians here. We know what "plus" actually means, and well, there's no sense in which "plus" fits.