Scorpiosis, I totally get what you mean about choosing to keep parts of your life separate. I often travel alone by choice. Why I do this is because so doing leaves me open to new experiences, usually within the culture I'm traveling in, that I would be far less likely to experience traveling with anyone else. If I were to encounter someone I knew on those occasions, I would not want to engage and would be very annoyed if such an engagement were forced upon me for any reason.

they can put aside their role as Therapist for the duration of the gathering

RT, while this may be your belief, it is not shared by most Ts. While you may determine your boundaries acc to the external circumstance, most Ts will determine their boundaries not as dictated by an association or employer (because there are few hard and fast rules), but by their interpretation of their ethical role as they see it. They will consider their personal comfort level, their clients' best interests, the response from the profession, their morality, and their intellectual perspectives about therapy. All are internal considerations.