I'm yet to experience a "false GP" so my information on it is based on research. A lot of research to be sure, but nothing more than that. In a previous life, however, I was an Examiner (and before that an ATO), and have seen several flight test candidates trying to intercept a GP from above. None of those attempts were ever successful enough to give me enough confidence in them to grant a pass, mainly because of the excessive rate of descent that led to overcontrolling and, therefore, going up and down thru the GP all the way down.
Well, at least they knew that they'd blown the ride before I'd said anything!
I trust that my suggestions to FWW were interpreted as being based on the assumption that he and all his colleagues already understand the "false GP" phenomenom and know how to recognise it in good time to do something safe. I don't intercept the GP from above unless I really have to, so don't want anyone to think that I'm recommending it.