You seem to mix-up "smart contracts" and the platform on which they run. On BSC, Binance effectively controls all smart contracts, since they control the chain

You seem to mix-up "smart contracts" and the platform on which they run. On BSC, Binance effectively controls all smart contracts, since they control the chain itself. And given that all bridges with the outside world are also centralized in a way, the only way for the scammers to cash out would have been to swap before anyone notices.