Foley is in bad shape but what else can they do? You don't want Ryback losing to Punk AGAIN, you don't want Cena losing to Punk AGAIN (though Cena can afford it, but that's not what WWE will want, he's the top, TOP guy), you don't have anybody else that's believable against Punk, or one that could sell as well, and this is a PPV where you don't need a particularly strong WWE Championship match, it's just one of those "get it over with so we can move on to the real story" PPV's.
I think Miz is gonna screw over Team Foley on Sunday, so that would throw a wrench into Foley vs Punk if it happens, how do you work around that, etc. I guess they could just not have that happen. If Foley turned into Cactus Jack, Punk would be able to sell that moment really well and it could garner some interest for the PPV. Granted, it wouldn't be a really hardcore, traditional Jack match, but it would threaten Punk and put a good story behind it, and make him look good when he wins.
The only other alternative I can see is Big Show goes over Sheamus, and then Big Show fights Orton at TLC and somehow Sheamus goes after Punk for TLC, but that would make NO sense because you'd be promoting Sheamus for losing to Big Show, but he's the only real person that I could see as a threat besides Ryback and Cena, who should not be taking another loss.