Thank you very much for your replies, they're pretty much spot on.
In any case, I completely agree that a generic claim system design allows for many types of claims, whether they are reputational or not, and whether they are "negative", "positive" or any other sort of qualitative category.
A reputational system (with "negative" votes, for example) can perfectly be implemented by using the general claim system that is already in place on Sovrin. How these reputational scores are to be used is up to the relying parties.
However, getting a bit more into the realm of governance: is there any work or consideration being done on how to measure reputation for the relevant actors within the system (trust anchors, stwards, etc.) and possibly by utilizing the very platform to do so? This pretty much touches the subject of Privacy Vs. Accountability, specifically the accountability aspect of it...