OP is very much in the wrong. You can't ride on the wrong side of the path (or road for that matter) and impact people who are using that side of the path for their rightful travel. Has nothing to do with hills. This is very obvious. If you're driving down the road and another car is driving in your lane but the opposite direction, honking (or yelling a verbal warning in this case) is not uncalled for.
Do not try this on the MUP I sometimes ride on, unless you can sustain an elbow strike to the head.