Its not about comparing implementations, its about the fact that a correct mempool implementation solves the problem without need for complex borrow checkers.

For example, in that implementation, you request memory from a mempool, it returns a chunk-struct with the pointer to allocated memory, the size of the chunk, and optionally some convenience functions for safe access (making sure that the pointer is not incremented or decremented beyond the limits). It also keeps its own pointer to the chunk-struct, along with the chunk that it was allocated. When you release the chunk, it zeros out the pointer in the chunk-struct. Now any access to it will cause a segfault.

You can of course write code that bypasses all those checks, but in Rust, thats equivalent to using unsafe when you wanna be lazy. Also you could argue that Rust is better because instead of segfaulting, the check will be caught during compile time, which is true but only for fairly simple programs. Once you start using RefCells, you cannot guarantee everything during compile time.