Dynamo, Difference between trans am and tour divide
In 2014, Mike Hall finished the TABR ~20 hours ahead of the second-place finisher.
Dynamo hubs impose a drag of 1–6 W when they're disengaged, and 1–25 W when engaged. There's a fair amount of variation between hubs, and in the loads that different headlights impose on them, and the loads vary with speed.
Ride Far has an analysis of how much time dyno hubs would be engaged in a bikepacking race and how much net loss they'd impose. This analysis is in terms of the TCR, not TABR, but even allowing for that difference, it seems that a dyno hub would add 2 hours or less to Mike Hall's time.
There are a lot of unknowns here. Did Mike Hall waste any time charging lights or other electronics when he would have been riding otherwise? Can we compare his performance in 2014 to performances in other years?

I think it's fair to say Mike Hall would have won TABR 2014 with an impressive time even with a dyno setup, and I'm surprised to learn he didn't use one.
The problem with relying on public facilities to recharge your electronics is that charging is slow, even if facilities are guaranteed to be available exactly when you need them. Headlights that might only deliver one night's worth of useful light (or less) can take 5 hours to charge (I'm looking specifically at the B&amp;M Ixon Space). Even high-capacity power banks with modern fast-charging capabilities (which didn't exist in 2014) can take 4 hours to fully charge, but could be used to recharge a headlight several times.