I feel like Waymo would have said something if it was the former, no?
Since there's a bike lane on 17th street, it's possible that the cyclist entered the intersection parallel to the truck on the bike lane but the truck overtook it. It's even possible that the cyclist was in the crosswalk for some reason...
edit: according to https://www.theverge.com/2024/2/7/24065063/waymo-driverless-... the truck was turning?
Was the Waymo car turning or was the cyclist? Because if the cyclist swerved into oncoming traffic there’s likely little any driver could do, but if the waymo car was ignoring the possibility that a cyclist was behind the truck that seems like a significant safety issue.