Hi, I would love to work on this project.
I would address this project with PHP and cURL - scrape answers, check them one by one for content(link) you've previously specified and downvote it(probably by submitting a form or just AJAX, I will have to check how exactly Quora handles this) until it's collapsed(again, I'll have to check how to test whether answer is collapsed or not, maybe the HTML it's embedded in contains a class that hides it, maybe they use some other technique).
Why did I write a description of how I would complete this project without even inspecting how Quora manages the actions such as collapsing answers etc? I used to create a demo for every job offering I bid on, but after so wasted time and energy due to not getting the job, even not getting contacted by the employer, I stopped, so feel free to contact me to request a demo or clarify any details regarding this project.
Best regards,
Kauri