First of all, this discussion developed from raising concerns around Safe Guardians selling OTC to the completely different question if tokens affected by an exploit can be somehow recovered or blacklisted.
To the last point neither the DAO nor the Foundation can blacklist any token. The Safe token doesn’t have a blacklisting functionality such as USDT/USDC. As mentioned in the previous thread by @daveytea the only recourse is to work with law enforcement and to potentially mark them on Etherscan or trhoughChainalysis. For this, the victim however would need to start this process.