What bugs me is, does my mere presence at meetings, service etc. actually encourage others on the fence to stay in. I mean, for many years I would think to myself, "This doesnt make any sense, but Brother AttendedCollege digs it and he's smart so what's wrong with me?"
Of course it does. That is what the organization is all about. Its about control in order to undermine or eliminate feelings of cognitive dissonance. Thats why people "leaving" is such a jarring thing with such jarring doctrinal practices. If someone leaves, it does not compute with their world-view of absolute truth and how a 'good' person could reject the group-think truth. Either people can accept that rational people will come to various conclusions about thigns like God, the Bible, 1914, and whether or not pant suits are socially acceptable (which completely begins to undermine the comforting group dynamic that is reinforced by ones entire association remaining faithful to the group world-view) OR people can eliminate what is causing that cognitive dissonance. How do they do that? The ostracize and shun those with the different world view. This allows for a rationalization ("this person just wants to live immorally; this person allowed Satan to take over their heart") and the shunning allows for that view to persist uninhibited.
So, yes, by your bending to show tacit approval of the witnesses means you are, at some level, reinforcing the delicate and persistent need for group members to reafirm that they are correct by seeing everyone they associate doing it.
Of course, you can say if you chose to fully leave, they will rationalize your leaving away and it may not make any difference anyway (by the mechanisms defined above). Thats fair and what you choose is really up to you.