Participation in a collaborative learning community needs to be addressed early on so the students know what the expectation is during their course. As long as there is a rubric assessing the student's abilities in the classroom, then there shouldn't be a problem with the instructor's "fair & equitable assessment."
If a student does not want to network or collaborate in the learning community, the other members should first try to speak with the individual to see where he/she is coming from. Once the community understands the individual's reservation in participating in a group setting, maybe they can help alleviate the individual's concerns and try to have this individual play their part. If still, the individual is resistant to working collaboratively, the situation should be told to the instructor, who then has a responsibility of speaking to the student and addressing their issues. The student should be reminded of the course expectations and rubrics for the grades - after clearly addressing the situation from Day 1, the individual should not have any excuses for not being able to work in a collaborative environment.