Rather late on this one and I give my apologies for that however, I believe it would still warrant a ban because it would just be seen that you can get away with intentional teamkilling, and teamkilling spree's at that.
I'll play this one like Rugby rules, for those who don't know, the ref can "hold" offences for a period of time if the victim team is at an advantage. In this case, your advantage is that more people have backed up your story.
Therefore, by that logic, I shall give this person a seven (7) day ban starting from now.
That means that his unban date and time will be; 07/12/2011 @ 00:00:00.