There is no such thing as the threshold of "threshold of not being money-hungry and now is in the community-building mode". What on earth is that idea from? Is it a capitalist view, that if you becoming immensely wealthy that your wealth confers benefits automatically on society? I'm curious.
Y Combinator is not turning into a charity or a non-profit. How does that make logic? It's primary intention is to make a profit. It is a business.
Part of that business is public relations and community management, but it's a business first and last.
Even if you'd drop completely selfless motives out of the picture (rich and eccentric folks sometimes fancy these and in particular this hackernews site seems to be pg's pet project), as far as I understand it, the long term success of YC as a business depends upon the long term success of Bay Area / Silicon Valley. If this is indeed the case (and if they don't need to squeeze every cent out of ppl right now), they may as well be in the 'community building' mode.
The original post had said "how critical public messaging and perception is to that business". Hmm. In my opinion, what is somewhat critical to them (business-wise) is this upcoming 10B DropBox IPO. Everything else doesn't look that critical to me. I doubt that a change to a comment system here can have any observable interaction with the IPO process. So I doubt that 'enforcing groupthink on a news company outlet' is critical to them and that it was it. Just pg working on his pet project seems more like it.
And if not. Oh well. Anyone who matters is likely to be intelligent enough to detect company bullshit/groupthink and this would be the end of it.