If the comment quality has eroded, is that because the standards are too lax (in which adding a new rule will theoretically fix it), or is it because of an Eternal September-type issue? If it's an Eternal September issue, then you have an enforcement problem: the upvote/downvote system is democratic, so the community would be unable to police itself against the new rule. The obvious solution would be to have people "more equal" than others, but then there's a possibility of groupthink forming and/or resentment against perceived "censorship." These are classic problems of Internet forum governance.

With all due respect to pg, one data point against the idea that it's just the standards being too lax is that this article was posted on Hacker News in the first place. The Hacker News guidelines state that most stories about politics are off-topic unless they are evidence of some interesting new phenomenon. I've never read tech news sites where the H1-B debate wasn't going on (I've been reading since 2001 or so), and based on the mountains of H1-B rhetoric I've read online, the arguments raised in the article are not new.