Correct me if I'm wrong (and I may well be!), but doesn't ram speed for the APU primarily affect the graphics performance?
Even with gimped RAM, an APU has plenty of graphics power for SC2 - the graphics settings won't matter in this situation. So the benchmark wouldn't change. Only the CPU side of the equation matters for (properly done) SC2 benchmarks. Does slow RAM also slow down the processing power of an APU?