I think it's on the belt line, but I agree it could've easily been called a low blow. It doesn't matter much tough, Judah had already quitted .
It was an evident low blow...period. If Judah was looking for way out is speculation. Khan was not hurting him just beating him. In the end, Judah lost via a controversial TKO...but it was a low blow and the fight is over.
Stomach, I doubt it is low. It hit the belt buckle. I wanted Zab to win but he got his stomach destroyed. Amir Khan won.