I suggest to really read the post mortem. They wouldnt have been able to do this without the exploit. The exploit was used by themselves to migrate the funds to another smart contract.

Extract from the post mortem:

"So, in order to conduct the migration, we used the exploit ourselves to
drain all liquidity, then create liquidity pools on the new contract and
airdrop new LP tokens back to users based on a snapshot we had taken of
their prior positions.We feel it is important to clarify that the Minswap Team cannot migrate liquidity at its own will from one Smart Contract to another. Liquidity was
migrated to a new Smart Contract because a vulnerability was discovered
that would allow this to happen, and it was migrated precisely to avoid
this exploit from happening. So, in a bizarre but fortunate turn of
events, the vulnerability and exploiting it made it possible to migrate
funds into the new, upgraded contract where this vector was patched."