I am not a SawStop owner but the question is simple enough to answer.
A SawStop tablesaw will NOT detect or prevent kickback or kickback related injuries. The SawStop works by detecting a small flow of electrical current between the metal blade and the metal tablesaw top, completing an electrical circuit that trips the pyrotechnics in the blade cartridge and retracts the blade (your body is electrically conductive, but this is also why the safety mechanism must be disabled when sawing wet wood and metal). An expensive event when it happens (you must replace the blade and cartridge afterwards), but much cheaper than the alternative trip to your local hospital!
Kickback is caused by either of two events: 1) an object being dropped on top of the moving saw blade and being accelerated by the spinning blade towards the user, or 2) the workpiece becoming trapped or pinched against either side of the blade (such as when trapped between blade and fence, case hardened wood, or reaction wood pinching closed or outwards against the fence) which causes the workpiece to ride up the rear of the blade resulting in the workpiece being accelerated quickly towards the user.
However, all modern (recent year) tablesaws now include riving knives that should always be left installed on the tablesaw (there is no good reason to remove them) and will greatly reduce the risk of kickback events by preventing the workpiece from pinching the rear of the saw blade. Additionally, for general sawing you may elect to install the larger riving knife that includes a blade guard and anti-kickback pawls to reduce the kickback risk even further. This is true of SawStops and all other legitimate tablesaw brands on the market today, but was not the norm more than a few years ago. So any new tablesaw, provided the riving knife is kept installed at all times, should greatly reduce the kickback risk versus an older tablesaw without a riving knife (or even a decent splitter installed). But even an older tablesaw can be made much safer if you simply ensure that a splitter, appropriate for your blade width, is installed at all times. Unfortunately, a ring knife is not a practical upgrade for older tablesaws as the riving knife must track up and down in coordination with the saw blade (and is attached to the actual trunnions assembly) whereas the old splitter and blade guard assembly was a fixed position install so be can not simply be installed as a substitute for another.
The above said, even most older saws (back to the 70s, if not earlier) ordinarily shipped with an integrated blade guard, splitter, and anti-kickback pawls setup that can be installed whenever making the sort of cuts that are at greatest risk of kickback (namely large sheet goods and ripping operations), though many of us regularly operate without such installed. I am in that group but I do install it whenever I am making a cut where there is an elevated risk of kickback occurring. I also make use of featherboards when ripping, for example, to greatly reduce the risk of kickback by denying the workpiece the opportunity to get out of line or ride up over the blade, which largely eliminates the risk of kickback occurring.