But a hybrid has an exponential amount of heat caused by pressure compared to that of a combustion
Do you even know what the word "exponential" means? An exponential relationship is " n<sup>x</sup>". Kind of like folding a piece of paper - the thickness can be found by 2<sup># of folds</sup>.
The pressure generated by various pre-ignition pressures is much closer to being linear than it is to being exponential. Not exactly, because of burn rate changes and such, but pretty close in ideal conditions.
A 2x mix should have about twice the energy of a 1x mix, and so on. If you'd ever fired a hybrid at 20x, you would have realised just how little heat is transferred to the chamber. And "making cool"? Every combustion gas gun I've ever seen was air cooled, and not even forced air. Just normal transfer of heat to the atmosphere until an equilibrium is reached. The chamber might heat up as much as 20 degrees or so on a high mix hybrid, but shocking up 20 degrees isn't going to have much effect on any chamber, nor is shock cooling by 20 degrees. The thermal effects on the chamber just aren't enough to worry about unless you're operating a hybrid at a few hundred x.