Charge/Block question

[UCFGUY06]

This afternoon I had a disagreement with a colleague at lunch. We were debating if what Shaq does posting up is a charge, block, or no call. My colleague said that when Shaq pushes people back with his butt that is a charge. I disagreed. It seems he wants Shaq punished for having a clear weight advantage and able to use some it to get position or post up. Is what Shaq does with his caboose any different then a smaller forward pushing back with his back?

Bottom line to what I am asking- When Shaq pushes people back with his butt is that a charge? The defender is behind him and not in front.

Thoughts? I bolded a part I thought was relevant that would make it seem like it was not a charge.

This is from NBA.com.-A block/charge foul occurs when a defender tries to get in front of his man to stop him from going in that direction. If he does not get into a legal defensive position and contact occurs, it is a blocking foul. If he gets to a legal position and the offensive player runs into him it is an offensive foul. In both situations, if the contact is minimal, no foul may be called. To get into a legal position defending against the dribbler, the defender just needs to get in front of him. On a drive to the basket, the defender must get to his position before the shooter starts his upward shooting motion. For most other cases, the defender must get into position and allow enough distance for the offensive player to stop and/or change direction.