This question of having a dual relationship as an OS facilitator seems an issue of professional responsibility that is analogous to the issue of therapists having dual relationships with their clients, which is strickly and unequivocally prohibited by all behavioral science licensing boards that I know of. While therapists know that many or perhaps most scenarios of dual relationships would be benign it is still a part of the professional culture to prohibit the cross over of relationships due to the responsibilties involved. If the professional culture allows everyone who practives to make their own intuitive and idiosyncratic judgement on the spur of the moment the profession is bound to eventually suffer from it.
Another point that is possibly relevant is that an interdisciplinary professional association I am part of has addressed the issue of creating an ethical code for this association with members whose "professions of origin" have codes that vary significantly regarding issues such as the tolerance of dual relationships. Our conclusion was that when the persons profession of origin had a more restrictive position on an issue than our association has, the more person was expected to adhere to the stricter code. I have both facilitated OS events and employed others to faciltate OS for my own professional group. Speaking as a consumer, if anyone I hired to lead an OS event compromised their professional responsibilities by abdication of the role of facilitator to indulge themselves as a participant, I would consider it unprofessional and a breach of responsibilty. Joe