Sorry "Standard", I had a relatively long and brilliant response written (ok, not so brilliant), when my browser (Firefox) decided that it was tired of working and shutdown on me all of a sudden, losing all I had written. So here's the abbreviated 2nd edition.....
It is part of the "Push, Block, Push" method, theorized by Chris Yeager, one of the hitting instructors/"gurus" talked about and followed by some posters here.
In 50 words or less...."
Push" with the rear leg to initiate the swing, "
block" the forward shifting weight with the lead leg, "
push" with the lead leg to complete the turn of the hips, powering the swing. Some people believe that that method of instruction is a sure cause of the "Shift THEN Swing" effect that is seen in those following it, that is not what is seen in the "Shift AND Swing" the is seen in video of high-level hitters.
Uh, yes, no, maybe so.....I think? Kind of confused at how you worded it, but I think you have the main gist of the concept.
The rear leg is the "driver", that powers and controls the timing of the swing, and the rear hip provides the resistance that keeps the pelvic girdle from rotating (opening??), until the resistance of the rear hip is "overpowered" by the rear leg, as the hitter releases it into the "GO" portion of the swing.
Note: For clarification of common/accepted hitting terminology....the "hips" (plural, one on each side), refers to the location/joint where the femoral head, meets the acetabulum of the pelvic girdle. While this area is well within the body, you can explain/feel its location be feeling the "greater trochanter", which sits just lateral to the femoral head.

**The femoral head (ball) sitting in the acetabulum (socket) can also be seen in this picture.**
The pelvic girdle is the singular bone structure that sits between the two hips, but is many times referred to, or confused by some as the "hips", as they feel, and point to the much higher "iliac crest" (upper left structure in the picture above). This is because when we were younger, and we told to "put our hands on hips", we actually put them on our "iliac crests".
Hope that helps, let me know what I can explain further,
mud -
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