Tbh if I were him, I'd level up to 99% to 999, and put the char on sale, see how high of a bid I can pull. I bet there's someone in this world who would pay really good money, not just to get that char, but to be the one to open the door.
I mean, guy has already wasted his years on the endless, mind numbing, super boring grind from level 300 onwards, might as well get something in return.
Whatever happens, excited to see what will be there.