I just wanted to add that in no way am I suggesting that the approach to Aggadita is in line with RSRH’s letter.
I am merely explaining why Slifkin takes aisolated parts of the world view of Gedolei Yisroel to suggest things that those who he use’s as his basis themselves condemned voceiferously.
However what I was taught by my Rabbeim (before Slifkin’s controversy BTW) is that the mesorah in the Litvishe Yeshivos was to approach Aggadita in line with the Ramchal and Vilna Gaon’s approach. And that the definitve peirush in regards to Hashkofa on Chumash was the Ramban.
As for Moreh Nevuchim I was taught the mesorah was that the Rambam had not learnt Kabbolah for what ever reason and therefore wrote certain things in Moreh Nevuchim.
The exceptions were those Gedolei Yisroel who felt Moreh Nevuchim should be read differently (not according to it’s simple meaning.) and therefore used it and devolped it.
So in other words the approach that Slifkin advocates was rejected by everybody.
All of which are of course rejected by Slifkin since he rejects Kabbolah.