And if the embryos do show they have it, he’ll know pretty quickly that he has it, I would think!
Not if he asks not to be told. They can be expected to find plenty of embryos with other much more glaring chromosomal abnormalities, so a number of embryos are going to be discarded no matter what. Even in young women, only about 50% of embryos are chromosomally normal, and most of the abnormalities will result in the embryo ceasing to develop either before or shortly after implantation. This couple may well have instructed the doctors just to discard any abnormal embryos, and not tell them what was wrong with them (just as many women have prenatal ultrasounds that make the sex of the fetus obvious to the doctor, but ask not to be told because they want it to be a surprise when the baby is born).