Thank you, that eventually solved it. I had to set the quest to 40 (console command "setstate mq01tate 40") and then talked to the guard and the quest was finished. The gate was still locked, so I used console commands to unlock it (open console, click the gate to highlight it, then type unlock). Then since the scripted death zone is still there in front of the gate, I had to use no clip (console command ncl) to fly around past it. Finally, the next part of the quest where the guy boats me to the Abbey did not start, so I set that quest to 0 (console command "setstate MQ01Porim 5") to start it and the boy talked to me immediately. The only artifacts of my workaround are the gate being present, and some non-interactable battle mages, and the death zone I'll have to no-clip around later.