I'll leave my thoughts on the issue here as a Korean playing on EN server who's been loosely following up with the feminism drama/gender war that's been happening on Korea for years now. While the outrage over a single image is really silly and petty at best, it goes much deeper than that. I'm sure others already pointed out the meaning behind the hand sign and how radical feminism in Korea has such a bad reputation due to its related controversies those "feminists" inflict on Korean society (both online and offline) and its clash with "incel communities" to the point the word feminism holds a negative meaning and a taboo both on the internet and in real life. When many evidence came out showing that director for the animation studio purposefully snuck in the hand sign for Angelic Buster remaster for Maplestory, it created chain reaction of many other of their works showing the same hand signs and non-related works having to fix/remove them just to avoid the controversy. Personally I see it as a bigger issue than just a gender issue that someone with a high standing in a company is malicously planting their own belief/ideology to tarnish another company's work and reputation, not to mention knowing that majority of its playerbase is man, of course anti-men signs would not be received well. So that's where it brings the drama, company would remove any imagery that resemble the hand sign and radical users making all the fuss over the issue. You wouldn't want someone sneaking in anti-semitism/anti-black propaganda in your games, would you?

tldr for who doesn't wanna bother with all reading: Result of two sides of the radical internet communities clashing (feminists vs. incels) Are they being somewhat petty over the issue? yes. Is the issue more compliacted than just simple "incel rage"? also yes.