I'm wondering first of all how you are coming to the conclusion that the pelvis is rotated posteriorly? To what degree are you performing the postural assessment? Just curious.
You also said that person has
"have restrictions in their external obliques,"....I'm not sure what that means either. ROM restrictions, as in rotational restrictions? Or are you palpating something that you are calling a restriction?
As far as the posterior pelvic tilt is concerned, I'm going to veer off onto a different direction all together. There is a posterior pelvic tilt and then there is a situation where the femurs are being pulled anteriorly. It looks like a posterior pelvic tilt but it is something different all together. It is my belief that a posterior pelvic tilt is not that common, but that femurs being pulled anteriorly is quite common.
People with a posterior pelvic tilt are a little harder to work with in my opinion. But folks with anterior femurs mainly need alot of iliacus type work--at it's attachment on the femur and the whole anterior hip superior and inferior of the iguinal ligament.
Now, I hear the protest, that I'm talking about anterior tilt/rotation muscles. But, I will fist fight anyone who tries to tell me that iliacus is in any kind of mechanical position to anteriorly tilt the pelvis. It can flex the hip, but it cannot bring the pelvis forward toward the femurs. Psoas can anteriorly tilt the pelvis indirectly because of it's attachment on the lumbar vertebrae.
And let me tell you, your guy ain't going to be able to swing a club if his abs are tight enough to be causing a posterior tilt of his pelvis.
*If I don't get back to any replies, it's not cause I don't want to debate, it's because my computer died and I'm just checking email here and there for a while.