Gyrochronology for A stars

As I struggle with my Song 2001 isochrones, I've also been thinking about why gyrochronology wouldn't work for A stars...

According to Simon & Landsman 1997, the onset of convection happens around B=0.2. Most of my stars have B-V<0.2, meaning they have a higher temp, and are therefore fully radiative. This implies that for those stars with B-V>0.2, gyrochronology SHOULD work if I can get periods for these stars. If they are fully radiative, they should have no outer convective layer for the magnetic field to couple to, and would spin down (SLOWLY) Skumanich-ly...

Barnes 2003 suggests the existence of a "radiative sequence" for A-type stars...