There's literally no way to prevent someone dedicated to ruining a game from doing just that. Whatever new rule Riot would make to allow for a remake in that situation, the troll would just evade it by doing the bare minimum it takes to disable remake. Meanwhile those additional remake rules would also be opening up the possibility of applying due to legitimate early game fights.
The only thing that can realistically be done is to report and ban the troll afterwards, and for their victims to just stop after the game, take a deep breath, remember it was only one game, and move on with their lives.