The owner of the website (in this case eschnou) is always able to choose what to display on the web page. Just like you can remove unwanted comments from a Wordpress comment thread, you can choose which "indieweb" comments to display.
My personal inclination is to accept any comments from people I know, and notify myself of any from people I don't know. I can then approve them/block them by adding them to my address book.
I can see a proof-of-work system working reasonably well (gets rid of mass-spams, though big sites would still get automated ones), but it seems like there should be something baked into it if this is at all intended to grow beyond 'indie'.