I am going to try to make this simple for you Artstation
1.) ban AI from this site and purge anything that is currently on it that obviously should not belong.
2.) automatic opt out, as soon as I post artwork. I would rather it that way with the option to opt in if I desire in the future (which I most likely won't)
3.) Look into designing a watermark that can scramble AI if we do have thieves that try to download images from here. Whether that watermark is some ugly scribbles, a noise layer that is hidden to human eye but not to AI etc
4.) OR what if Artstation was made to be private and only accessible to the users that make an account to be on it?