you can't just de-AI something. You would need to rewrite the whole thing yourself, which nobody wanted to do in the first place, that's why AI was used.
Source codes public and you can see all the code the AI changed in the commit history. The actual physics engine is not AI, it's Box2D which is open source, https://box2d.org/. Feel free to go through and rewrite the portions AI wrote, I just don't write C++ code and don't have time to understand the codebase for TBT and B2D well enough to integrate the two of them.
Now that we know it's possible to swap (merge?) TPT's physics engine with something that's capable of handling moving solids, I see the potential for a renaissance of C++ mods. Using something like LiquidFun (which is closely related to Box2D) could enable things like soft bodies and rigid-fluid coupling, both of which are known to be incompatible with TPT's current physics engine.