Yes, worse. Dumbledore said, "Hogwarts needs an evil Potions Master to be a proper magical school, " in chapter 18. If he is willing to allow the abuse of children to keep an evil potions master, we might believe he would abuse a sixteen- or seventeen-year-old to make an evil potions master.

This is a case of You Just Told Me - Harry offers that excuse to Dumbledore, who then goes on to repeat it back to him.