Why so rude? All he did was ask for a feature that many games gave
He did not ask for anything.
"Hey, I can't load my saves with the newest update. Is that something on my end, or is this a known issue? Can you add a feature to jump to the newest content in a future version?"
That's what asking for something looks like.
What he did instead was to complain, or to demand, depending on your interpretation of his words. Neither is really that great of an approach if you want someone to do something for you - especially if you expect them to do it for free.
If you don't pay for it or suck his D on discord you aren't allowed to comment or have an opinion about the game what so ever. Numerous very good ideas have been given previously on a certain pirate site and Vertigo always loses his shit, always goes on about 'entitled people' and 'free', imagine being such a pathetic dev you disregard good ideas and actually improving your game because those people don't pay.