I totally forgot to post it here. This game is fun! (except the 40 peanuts gathering part grrr!)
Thank you! The graffiti artist is an in-game help system. You can totally complete the game without using the help. I made it a bit inconvenient to collect the peanuts to discourage using the help system and encourage solving the puzzles in a traditional way.
I indeed realized that some options disappeared because I've already completed those without his help. But I remembered he needed 40 peanuts, so I got them, without realizing I've already completed that task by the time I got 40 peanuts XD