There is a way to disable the MDS with a handheld "tuner", but simply pulling a wire won't do--the computer would just diagnose a fault with the system and I'm not sure how this would affect the vehicle's running.
Since your problem appears to be mechanical, simply making the system not work any more would not help, in my opinion. The mechanical components that make the system work appear to be damaged on one cylinder, and you would be left with the same problem. The truck's computer isn't calling for the system to be activated anyway when you first start the truck--the truck must warm up to a certain point before the computer tries to use it, and then only under certain driving conditions. To mechanically disable the system would require replacing the valve train on the engine, which would cost more than the repair.
Does the dealer have any theory as to why this broke? For example, do they think that sludge in the engine may have caused it, incorrect oil weight may have caused it, or??
Finally, since you say the oil gauge is "pegged" at startup, it might be worth having the dealer check that first--even if you cannot access the oil pressure on the truck's display, it should be easily accessible with a scan tool, or if all else fails, by testing with a mechanical gauge. A pegged oil gauge does not sound normal.
It also may be worth appealing to a district manager or Chrysler to share some of the repair expense for this. It couldn't hurt--they at least might cut your repair bill down if it comes to that.