It's time (Option to Hide other players Glamour)

[Penthea]

So it's not okay to modify a copy (the game client), but it's okay to modify a copy of a copy (the screenshot)?

Yes, just like how it's okay to take a photo of a building, and draw on the photograph but it's not okay to tamper with the building itself.

EDIT: to clarify the game is SE's property, and using mods that change how that property looks does infringe on their ownership rights. But using third party software to edit a screenshot is not. Because the screenshot is not the game.