Popa, by our traditional definitions of apikorsus, one has to agree with your observation about this individual. And coming from someone who is guiding others in a religious leadership position, it is even more of a violation of our mesora.
I do have a question, though.
In our day and age, it is simple enough for any individual, Rabbi or not, to simply disengage emunah in anything, altogether. In fact, I would argue, in most western cultures its easier to be an atheist than it is to hold any belief.
In this respect, our reality is wholly and completely different, than, say, the Rambam’s, where perhaps the only thing more dangerous than being a Jew was being a total non believer.
Setting aside this rabbi’s position of responsibility for a moment, must we as frum Jews look exactly the same way at someone who says – its all a fairy tale – as at someone who says – its written in more than one voice, a singular revelation collected over a period of time?
I don’t know the answer, I’m not presupposing it, but that nasty bugaboo of critical thinking that we can’t really avoid rears its head again, and if we say, yes, its exactly the same apikorsus, then it is perhaps incumbent upon us to reasonably explain in a Torah context the elements of the text that are giving him and those who follow the documentary hypothesis their ammunition.