Because she got the D. She doesn’t know he’s shooting blanks.
Also “sterile” doesn’t mean “no fertilization”. I think the way they do it for mosquitoes is that the males fertilize the females, but the offspring are unable to develop and hatch. To propagate the males in captivity, they modified critical genes to require specific laboratory conditions to activate. In the wild those genes can no longer function and the eggs don’t hatch.
Now do salmonella like the rest of the civilized world