Following on from my previous comment, I think it would be better to focus on avoiding *actual* conflicts of interest. I think worrying about appearances is what happens when there is a lack of understanding of the substance and, in the case of managing a useful and productive collaboration between the community and NCC-as-secretariat, the substance seems important.
If the goal is to avoid a need for understanding, then it seems like the natural solution is that NCC staff should never be allowed to participate as members of the community at all. I don't think that is necessary or desirable.
Joe