Even a hardened conspiracy theorist such as myself doesn’t think it was Mab. She literally cannot put her finger on the scales of justice.
I like to think given Max’s knowledge of the supernatural that she is actually a wizard herself now off the grid from the WC and now looks a couple of decades younger than Max, when they started off the other way round. She may therefore have knowledge surrounding Harry’s birth.
More likely her character didn’t need to be fleshed out at this point.
