Does it really get that hot? I thought the plug gets about 450 degrees F, seems like a massive jump to 1200.
Exhaust gas temperatures in a correctly jetted two-stroke will run around 1200*F. When the temps start approaching or exceeding 1300* bad things start to happen. If the temps are less than about 1200*F then the engine is not effectively extracting the energy from the fuel. Combustion temps can exceed 2800*C (4500*F).
The plug, piston crown, cylinder, and head are all cooled by the cooling system. They are also protected from the extreme heat of combustion by a very thin boundary layer a few molecules thick of unburned fuel fuel that clings to the surfaces. Otherwise they would melt.