What does the parking brake have to do with the pilot walking into the
prop?
Getting anywhere near the front of an airplane with a running engine is
something you just don't do.
I'm figuring he did one of two things. It was cold out, so he thought he
would start it first, let the engine idle and warm up while he finished
the
walk-around, or he forgot to pull wheel chocks.

he had already taxied to the departure end, it was in the original posting..
BT