As long as this is not escrowed you should not wear the signature. Note that if you add the signature it appears under all your previous posts giving OP and his projects free exposure and you get nothing. Apply without using their signature and wait for the funds to be confirmed. Don't help scammers!
This seems exactly what the OP aims to achieve. It is even more surprising that most high ranked members (Senior - Legendary) of this forum don't even see through this yet.