HP and torque are just words to identify a work force. It's the work force that's doing the work, not hp, and not torque. It makes no difference where they cross, because if you call them somehthing else, they may cross in a completely different place...just depends on the converson factor. (look at metric power conversions) Torque is basically a stationary work force...hp is torque which has been converted to relate to time and distance (RPM) using a conversion factor. They're both basically saying the same thing. Because of the conversion factor (and nothinig else) hp and torque cross at 5250rpm. Below that, torque will always be higher than hp, and above, the opposite. That's why it "seems" as if lower rpm is torque related, and high rpm is hp related. It's only a function of math, not the work force being applied.
Hope that helps a little.