Problem: as soon as I transfer ETH to my wallet they are immediately send away.

Hi, it's a bit more complex:

Someone contacted me for help. He has an ethereum wallet with some tokens in it and he can't transfer them out of the wallet. As soon as he transfers ETH into his wallet, they are immediately send away.

How can he solve this?

I try to write a python script that sends the tokens to another address as soon as ETH appear. Its my first time interacting with web3 and python and I fail at specifying the ABI correctly to check how many tokens are on the wallet.

But I have in mind that the thief might check each block whether he sends ETH to this wallet and immediately creates an order to send them to the thief's wallet. Would he be faster than me? Should I create multiple orders around the time when I expect the ETH to appear?

Is there any solution to this?

Edits: additional info