Qwerty and Coffee,
I’m still waiting for you to come out against the Vilna Gaon who said the same vort as Rabbi Posner.
By the way, once your at it, I found that the Ben Yehoyada says the same vort (סנהדרין פט,ב), so I expect you to come out against him as well.
(And again, the root concept that without the tenth test the first nine seemed worthless is a clear Gemara and Rashi on Chumash, as well as hinted in the posuk “NOW i know that you fear Hashem”.)