Kind of reminds me of when I had jury duty in BOS on 9/11. We were a group of about 20, following events by radio and asked to just "sit still" until the courts sorted out what to do. After a little while, I went to the bailiff and said, "clearly there won't be any trials today. I'd like to go home." He said that everyone was asked to stay. I asked him what would happen if I walked out. He shrugged his shoulders and indicated he wouldn't chase anyone down. I informed the others I was leaving and each could decide on their own. Everyone walked out after me.
I never heard back from the courts and I assume they considered my obligation fulfilled. Too bad, as I'd like to serve on a jury
Anyway, to the OP's point, I think that you were in a situation where there is "reasonableness" and there are "rules." Even if there was a "rule" against what you did, your action seems reasonable to me, and forcing you to remain on the plane seems unreasonable.
[N.B. There are other times when I'd say that getting off is selfish and unreasonable. I was once on a delayed flight BOS-ATL. Some people who would clearly miss their connections wanted off. This would have caused a greater paperwork delay, and caused
more people to miss connections that they had a shot at making. In that case, it would have been thoughtless for those people to disembark, which they did not do.]