I had their rejections in email. Ultimately, the committee brought them around and accepted my thesis so I didn’t feel it was worth burning those bridges.

What would that get you though, other than knowing you were right (which you already knew without having it in writing) and (if you decide to publicly call them out on it) enemies for life in your chosen field of study?

Oh, I wouldn't do it publicly. The point would be to push back, in private discussions, against the argument that the result was not interesting enough to publish.