Where have you seen this, and what was the argument for it? First time I’ve come across it. Unless there’s a compelling reason I don’t see the need to change the name because it’s gendered. Is “harvestman” even a term used for anything else these days?
I’ve always found “harvestmen” a weird name, but apparently (at least according to Wikipedia) it stems from “harvest spiders” or “shepherd” (which is what opilio means in Latin).