[STFUjiujitsu]

If you did that and his hips were already swinging out than you are simply helping him your head down to trap that arm tigher.
If anything posture up when he starts to throw that leg around and prevent him from getting it across your face.
My favorite counter is hard to explain but when he throws the leg over push your hips into his and roll over your butt and because his leg is tied up with your arm his hips follow over top your hips and you land in a top position.