The ball still goes back to Rodgers.
Go for two, you have one shot to win. If it works out, great. If it doesn't that's it.
Kick the XP, assuming it is good, you give yourself two chances to win. Defense gets a turnover. Or, get the ball first in OT and score a TD. Harbaugh supposedly has guts for going for it, but he was actually afraid to trust his defense which happened to be fighting it's ass off or there would've not been a game at all.
So, that is how I see it. I also thought him going for it instead of kicking FG inside the 5 was a bad decision. Almost as bad as KK doing the same thing today. These coaches have some kind of brain fever with all these 4th down attempts.