When playing 3 player do you play 'attack the person to your right'?
If you're just playing 'last one standing' and faced with those two opponents, I would probably turtle up. Make yourself a harder target than the other turtle and the aggressive player will go after him/her.
But I think the better solution is to consider other options for how to play 3-player, like Scorpion suggested above. Though I prefer "winner is the one who deals the most damage" over "attack right" (or "attack left").