it doesn't matter if your dns resolver leaks part of your ip address to archive.is's dns servers when you're about to connect to archive.is from your ip address anyway. the only thing dropping the edns client subnet does is prevent services you use from giving you a server that's closer to you when you do the dns lookup. this performance issue, of course, does not affect sites using cloudflare.
That you might connect to archive.is directly isn't of any concern. You might also not do that, and they've decided that leaking data about the user isn't what they want to do.
It's not anticompetitive. It's not evil.
Did we read the same article? Cloudflare is treating them, and anybody else that makes the same choices wrt EDNS, differently from the rest of the Internet.