Maybe direct replies to a comment below -4 shouldn't appear in the Recent Comments feed, and perhaps direct replies to anything else posted by the same user within the same thread?
I like the first half of that, but not the second. It is possible to say something stupid and something worthwhile in the same thread, and it would be unneccessarily confusing to have replies to non-downvoted comments not showing up.
A brief line from this comment indicates that the author of the cryonics-critical comment quoted here was perhaps not the one that deleted it.
Was it deleted by a moderator?
Honestly, the decisive downvoting seemed to do the trick of hiding it from casual readers who don't want to see the long annoying rants. I don't think it was casting any doubt on the credibility of cryonics.
While it sounds like the author regrets posting it, I would think they should be allowed to delete it themselves.
Edit: Originally titled "Cryonics critical comment deleted?"