Considering the researcher had already reported these to Microsoft, and delayed releasing them publicly until Microsoft "pulled every childish game possible" (quote) instead of patching them, it's not unreasonable for the researcher to be withholding another exploit from the public to limit harm.

I also disagree that the PIN bypass would be "10 times more impressive," but that's just my professional opinion.

If you think about it for some minutes you will maybe understand that there are many reasons not to publish it.