I think Seb would fight Kimi joining the team. He may have no choice. But I doupt he would enjoy such a strong team mate taking points from him. You just have to look at 2010 when Mark was taking points from him. Turkeytastrophy.
Greenlantern101 - If Seb ends up being the deciding factor keeping Kimi away, then every suggestion that this guys behind the scenes petulance knows no bounds will have been proven true. It would be the most embarrassing episode of his career if it was ever publicly acknowledged that he indeed "vetoed" Raikkonen's arrival.
You would really like to think that a (soon to be) 4xWDC would be confident enough to take on another top tier driver in equal machinery. Although I suppose I could see why he might be wary of this prospect, seeing as he hasn't faced such a challenge since 2006 when Paul di Resta beat him to the F3 Title in the same car.