just transfer your money on another card after the paypal payment, and only then send the bitcoin
he can't transfer back in this way
solved?
This is the right way to go. Make new fake detail paypal account over VPN or new IP and accept the money. Then send that money to your main paypal and close the fake paypal's account. The money does not get charged back from your main paypal because as far as paypal can see you are a different person and you can't be put into debt because of someone else's doings, the debt is down to the fake paypal. Unless it is for thousands of dollars paypal aren't going to do anything about it.
This is a handy method for selling stuff for paypal without risk. If you were an official company then clearly there would be problems but as some guy who sells bitcoin nothing will come out of it.