It's not a rival at all.

-You can only have a finite amoutn of rivals. Eveyr team on your schedule can't be a rival. Ga Tech, Florida, and Auburn are unquestioned, undeniable, absolute no-brainer "RIVALS" of UGA football. That's about the max we can handle
-We have a long history of palying SC but longevity is only one small part of the equation. Prior to SC joining the SEC, UGA held a 33-9-2 advantage. Inbcredibly one sided
-When SC joined the league things did begin to go their way at least som eof hte time. They got a big win over UGA in athens in their 2nd year in the league. They had a magical 2000 season that included knocking off a highly ranked (at the time, we'd lose 4 games) UGA team. This added fuel to SC thinking they were a rival of ours.
-When spurrier got there in 2005 it kind of got some UGA people getting on board with the idea too. Had aboslutely nothing to do with SC and everythign to do wiht the coahc. There were some really great contests over this 10 year period.
-Post spurrier it's been more of hte same as usual with UGA dominating more times than not.

SC is a school that for most of the teams' histories has barely reigstered as a blip on the radar, but for a very few brief flashes has been quite the thorn in our side before reverting back to their substandard norm in short order.