It's a funny joke, sure, but it's functionally "end the quest" as a vote. Do you see a future for the story here beyond the point where we make that vote? Something beyond the inevitable bad end for us and whoever we managed to take down with us? Something that continues pulling on the threads that have been laid all this time? I honestly don't. Best case scenario, we get an epilogue-style view of the fallout and then start over from scratch with a new character, and even that throws the vast majority of what we've built here out the window.
I like this quest. I want to see it keep going, I want the stuff it's set up to pay off. It's only natural that I would be upset at other players trying to unceremoniously end it all, laughing all the while. It's just not funny when someone points a gun at something you love, and says they'd actually be fine with pulling the trigger. Call me a killjoy, call it 'tiresome', I'm not going to just keep my feelings to myself when you're threatening something I care so much about.