My impression of the other convicts was that they were regular convicts, not 'military'/Starfleet ones like Burnham. That doesn't rule out the chance that they have advanced degrees (since this is the mostly evolved 23rd century), but lessens it, especially since they don't seem to be your average 'white collar' criminals one might expect from this era.
In a novel I read, they called it Eugenics War Fallout.
A few thousand men and women as strong as a triceratops, and smarter than a calculator screwing thousands, maybe tens of thousands of regular people, and their babies screwing 10s of thousands, maybe hundreds of thousands of regular people, and their babies screwing mi... You get my point?
Unless the Supermen did not breed with normals, or they were sterilized, or tossed into mass graves, or superhumanism was nonhereditive recessive junk DNA, their continued expression in the gene pool was uplifting, especially as the grand children of different Supermen started falling in love and wondering why their own children could speak 5 languages before they could walk.