Ukraine's strength of male population is in the 35-45 y/o bracket. In many ways, such men make better soldiers than the younger men, anyway. (This is not 100%, of course.) And most ~40 y/o mens' children are mostly grown to young adulthood, so their losses in many ways affect their descendants less.
So, you and Graham share a similar ignorance. You I can forgive. Graham's staff should brief him better.
Jeez, I can see why they have a draft age starting at age 27. Adult males under age 27 apparently have left the country. Along with most of the young women. So lowering the draft age would likely have minimal payoff. Following the news (not on mainstream media but via YouTube and other online direct reports) it appears that many remaining males are attempting to flee the country).
Bottom line is that Zelensky will continue feeding the 27s and older into the various meat grinders.
They'll just have to wait for the young guys to turn 27. In the meantime, they need to build more drones.