Cyclists are supposed to stop at stop signs, if not stop at least yield. At least in this case (if true), the cyclist followed the truck through a 4 way intersection (assuming it's a 4-way stop), that would put them in the wrong.
There’s rules as written and then rules as followed — I’d much prefer a system that recognizes the rules that people tend to follow/bend/break — as a cyclist I too will often “convoy” with a bigger vehicle as it provides some additional protection most of the time (though obviously not here)
As a bicyclist in San Francisco, if I follow the rules as written, I cause traffic. Cars expect me to blow through four-way stop-sign intersections, and if I stop and wait for the cars, the drivers get confused & don't want to go (afraid of hitting me, I suspect).
In terms of right of way, the rules as followed seem to be pedestrian > bike > car.
I sometimes give way to bicyclists at four-way stops because I can't be sure they didn't get there before I did and I didn't see them because they're small.
And of course, if a vehicle, be it a bicyclist or car, enters an intersection when I have right-of-way, it's not like I'm going to start crossing and intentionally run into them.
Where bicyclists really risk their lives if they start assuming cars will give way to them is when they blow through two-way stops, especially at night or at one of the many intersections with poor visibility.
Note that there are bike lanes on the likely street where this occurred. The cyclist was not necessarily following the truck but could have been parallel (and overtaken).
Hope waymo releases the footage.