I had a bad feeling just reading the initial post, before thinking about any specific drawbacks. But this? If you failed to notice that your system would result in many users being arbitrarily and permanently banned, what else have you missed that no one else has pointed out yet?

Personally, I wouldn't read a "pending comments" page, because I come to HN to read and discuss stories that interest me, not to browse piles of random, context-free comments. I suspect that most users will feel the same, so it won't help much.

This entire thing is a bad idea, and the current state of Hacker News comments is nowhere near bad enough to warrant such drastic measures.