the first obvious question is why is a neurosurgeon involved? why don't they ask Simon's doctors or at least an oncology expert?

In my area, BCL is short hand for B-cell (memory cells involved in regulating the immune system) but I am not sure if this is what it refers to here (wonderful thing about medicine - the same nomenclature means different things in different disciplines). BCL2 positivity was floated as a marker for prognosis in cervical cancer years ago but results were inconsistent, and as far as I know the idea just petered out. I am not sure what possible connection this would have with Simon unless his lab results indicated a BCL2 positivity and research into correlation between BCL and HPV has progressed into head and neck cancer. The first step would be to check the references that the neurosurgeon has provided to make sure he isn't applying results from cervical cancer studies to Simon's case. If he is, another expert could easily rebut such a conclusion.

My only reading of any connection between BCL2+ as a marker for prognosis and HPV is in cervical cancer. For every experiment that found a correlation there was another that found none.

Might I suggest you or Simon talk to his radiation oncologist and get them to look at the report give his view and possibly explain the significance of the neurosurgeons conclusions?

sorry to be so vague - I am really not following the thinking here ...