Thanks for the comments!
In reply to your questions, you are absolutely correct that the PCs are delivered right to the assassin. That was mostly so that I could contain the entire encounter in a single pamphlet (which I really like doing). Building out a bit more of the situation would probably require switching to a zine, with a tables of rumors and hooks, maybe a point-crawl through the city to find the assassin, etc.
As for helping the corpos, that depends a bit on what the PCs decide to do once the encounter begins. Could they subdue the assassin and bargain with them? Could they take out the assassin, but then make off with the assassin's gear instead of reporting back to the quest giver? Again, you are correct in your assessment that the quest giver works for the corpos the way I wrote it.
In any event, I am glad that you enjoyed reading it!