In my book, a harrier is any forward flight (inverted/right side up) where the wing is flying at a AOA past the threshold of the stall, i.e. your in the high drag bucket part of the lift curve.

Throttle isn't used to prevent the wing from stalling... the wing is already stalled. Throttle is used to keep the stabs unstalled, i.e. flying so they can provide the needed down thrust required to keep the wing at a high AOA. Most aerobatic wings will probably stall at a AOA of 15 degrees. Now this is AOA, not attitude with respect to ground, but still, if your 30 degrees nose high and crawling along, I guarantee your wing is stalled.

Simple vector analysis should intuitively prove to most that the engine isn't providing much in the way of vertical thrust if your doing a 30-45 degree harrier at low throttle. If I harrrier at about 0.5:1 thrust/weight and I'm at a 45 degree angle, I'm only directing 0.25:1 thrust down... that means the wing is still responsible for 75% of the lift.

I'd consider a 70 degrees nose high attitude a hover, not a harrier, but that's me.

Cheers