When the ??”? said you can shave on ??? ??? when ?”? ????? falls on Sunday, he was going ????? that the ??????? of ????? begin on ??? ???? and go to ?????. In this case, you don’t have the option of shaving later in the week, so there is a ???? to shave on ??? ??? so that you don’t shave right after ???. But most of us who end the ??????? of ????? on ?”? ????? wouldn’t be able to use that ???? because we could avoid the ????? by just shaving later in the week.
And why didn’t the Rema just say you can’t shave on lag b’omer either when it falls on Sunday? What mitzva is there to davka shave on lag b’omer?