You both raise valid points, but that does not preclude the young Warden commander from being captured by the Architect in Awakening. I am not certain either that age would effect this breeding business. If you follow the rhyme that the tainted dwarf uses in DAO, it appears to be magical as well. The truth is that we don't know if they can breed after that, but I must agree with German Soldier that female wardens are "the stupidest idea ever and should be forbidden." Not that women can't fight, but since females can be broodmothers AND the Wardens know this, it is simply another we do as we d*mn*d well please attitude. Anything to achieve their goal no matter how sordid that might be. UGH
For all we know, the Architect doesn't want to turn the Warden-Commander into a Broodmother. The proof is Utha, who is living with him since 9:10 Dragon, and isn't a broodmother, just a ghouled dwarven woman with free will. He wants someone who can help him, and turning the Warden-Commander into a broodmother doesn't help him to achieve that.
And that transformation involves more that only being tainted. Involves some sh** about a lot of darkspawn raping the poor woman, given her some stuff to eat (fluids, flesh and that). That means that female Wardens don't just mutate into broodmothers if they are careful and die before being raped. They just became ghouls, like Utha (who was a Warden, btw, and somehow proofs female Wardens don't turn into broodmothers).
Only because the Architect approached a potential female Warden, doesn't mean she was in danger of becoming a broodmother.