System (TCPIP.SYS) recognizes SYN-ACK only when it was establishing the connection (sending SYN) itself. To force TCPIP.SYS to accept SYN-ACK you would have to modify TCPIP.SYS internal structures.
Normally if you are trying to establish TCP connection with WinpkFilter you have to process SYN-ACK yourself without passing it up to TCPIP.SYS and generate ACK to complete the handshaking.