The art he offers is random, too, so what you get will likely be different than what someone else gets.
Talk to him and wait for him to apply his family discount and buy the first art he sells (it will always be genuine), and then give it to Blathers.
While his boat will always be docked on the small northern beach on your island, you won’t be able to enter it until you find Redd himself wandering elsewhere on the island.