I agree with the person who said to say no and take your role anyway. If he walks to your lane and tries to play your role during the game, then report him. Obviously, his doing so could make you lose, but so would letting this troll take your role and make you play support. At least you get the sweet satisfaction of the instant feedback report that way.
Regardless, report him for griefing because he stole your role and harassment because he no doubt demanded it harshly. Also, if he walks into lane to take your role, then also report him for intentional feeding, since every one of his deaths could have been avoided had he just played his autofilled role.