It's obvious why an uninvited conversations are perceived as a sexism.
But anyone with the experience in almost anything but particularly in any trade would tell you what men do receive uninvited conversations with men bent on signaling their expertise all the goddamn time.
Sure, seeing 'a woman out of place' triggers some of them to do it when they wouldn't do it with a man in the same place, because they could get told to shove their oh-so-important opinion to the place where sun is not shining, but the source of this behaviour is not to be a sexist asshole but just being an asshole.
As the other comment rightfully notes, any difference is going to be a target.