It is.
Currently I add the random person's fork as a remote to inspect/modify their PR branch. Was hoping for some GitHub magic to eliminate this step.
This can be a pretty common setup for some git workflows. Everybody makes a fork and takes / pushes pull requests or branches from their fork to others. The main advantage would be that if you have a lot of branches they don't all have to be on upstream and you don't need to have upstream permissions for everyone to push branches or changes to.
Nonetheless, I can see why my comment raised some confusion.