It doesn't say the Tribe that WINS gets an unexpected reward. It says the IC shocks them with an unexpected reward.
Thus I'd like to suggest another possibility. I think the Immunity Challenge itself will directly involve the unexpected reward. That is, the challenge will be to recover or find this "reward" which I believe will probably be their personal belongings.
If the rules are that both teams get to the keep the reward or whatever portion of the reward they recover, but the team who recovers all the fastest, wins immunity ... this would allow for the possibility that Morgan could be the loser, but still be holding the whiskey bottle ?
Could Osten have cost Morgan yet another IC and thus be the lubricated spectacle at TC perhaps drowning his sorrows ?