This isn’t a scriptural challenge to universalism per se, but a philosophical one.
IIRC Talbott does not believe in middle knowledge. I too happen to find the idea incoherent. This thread is a question for universalists who believe (1) in free will and (2) that God does not have middle knowledge.
Premise 1: God would never create a person unless he knew that that person would be saved
Premise 2: Every person has free will
Premise 3: The idea that even an omnipotent being could know what would happen in circumstances that never come about, is incoherent
If we accept all three premises, do the odds of universal salvation happening, just as God wants, become virtually impossible?
Choice 1 (C1): create man
Choice 2 (C2): do not create man
If God has middle knowledge, then prior to creating man (Adam), God could have known the number of people who would be saved and damned in the event that he chose to create man, and based his decision on whether or not to create man on this knowledge; if C1 would lead to a single person not being saved, God would choose C2. But what if man has have free will and God doesn’t have middle knowledge?