Most likely they emulated the cpuid corresponding to a previously existing Intel part. cpuid is used to fill in those “GHz” numbers you see in these reports.
My guess would be that's the base freq it will go to under full load on a fanless MBA. It's like the "official" 1.1GHz base clock of the i5-1030NG7.
I wonder if this is a hint that Rosetta 2 on the 3.2 GHz M1 is intended to provide equivalent performance to a 2.4 GHz Intel processor.