There's no doubt he's going straight after the Rock. HHH just got so played out with that Orton fued. He took his time off and now he's ready to be back in the ring full time. The Rock coming back and looking/doing so good has got to be messing with his pride a little bit.
Hunter is a businessman, and I'm sure he knows that having Rock around for a while is good for business. However, Hunter may be the heir apparent to the throne, but Rock is a bigger "star" in and out of wrestling. So, I agree with you that Rock's presence likely has some
effect on his ego.
HHH can at least take solace in the fact that Rock will not be full-time.