Great work! I really like your metaphor and think you have done a great job of presenting it visually.
I am particularly interested in your angry encounter with another learner on your course. I felt that my MOOC was so big and had such a diverse group of learners with a wide variety of motivators, that I would have been very surprised to see an individual challenged based on their reasons for being on the course. I found there to be a very selfish ethos within my MOOC and nobody seemed to bother with what anyone else was doing.
I did notice, however, that you said your course wasn’t very big.
So I wonder if people who are aware of the size of their online community behave in different manners. Perhaps the person in your encounter felt that their voice would be louder in a tight-knit community, rather than drowned out in the masses?