“...no scriptural basis...”
Matthew 19:12; 1 Corinthians 7:37,38
Virginity is not required according to St. Paul and St. Matthew, however it is preferred as the better way - since the priesthood is voluntary, men entering the priesthood knowing that it requires celibacy (”eunuchs - although of course not literally) are choosing the better way (”eunuch” for the kingdom”)
here is no scriptural basis for it being required.