You're describing a HU match.
Which advantage are you referring to? It's not position, since HU you will alternate being in position.
He is describing a situation that is probably a freeroll, as buy-ins usually show up. At a cash game, sit-outs are removed after 3 orbits, at least they are at Full Tilt.Anyway, at a full table, the active guy on your left is at a
huge advantage. Every time you fold, he is in position to steal
everyone else's blinds unchallenged. It is not at all HU. You are in the worst position in all but the 1 hand when you get to be dealer.
With regards to the OP, don't know what to tell you, it sucks. I suppose you could be more aggressive and raise with a very widened range. Your opponent simply doesn't have to work as hard. And his range will widen as well. I've been in this situation a few times. Sometimes we'd befriend each other and take turns, sometimes, the guy ahead of me is a ***** about it. If I'm acting last, and the guy behind me calls, I'll let him have it unless my cards are good. I like to play fair and keep the peace. If he's raising a little too much, I 'adjust'.