So you're proposing they could be in a situation where they can either:
1. Publish an untruthful blog post, relying on public data available from multiple parties, trying to somehow explain it all while avoiding talking about their involvement in a way that would get them in PR, legal or political hot water; or
2. Publish nothing.
And they chose #1?
The only way #1 makes any sense at all is if some greater consequence to not publishing was put in place. But that would be more something like "the US gov essentially forced Cloudflare to write this" than "Cloudflare was part of this".
Unless they were part of this, _and_ the government forced them to write a post saying they're _not_ part of it and...
For my money: this is something in the news making it a good marketing opportunity which is ultimately what the blog is--trying to market Cloudflare and the brand to technical crowds.