I am not planning on debating the subject of which topics of “agada” are subject to Halachic decision.
My point is that leaning to one side of an issue due to logical reasoning and proofs from the sugya have no relation to “deciding” how one “holds” based on their “belief”.
I can say that based on whatever proof or svara I “hold” like R’ Sadya (still presumptuous, but all right). But to therefore say “I don’t believe in gilgulim” is not the same thing.