(Symantec accidentally signed a SHA-1 certificate from a publicly-trusted root while preparing their SHA-1 issuance exception application, but that's not quite as bad, I guess.)
It would be a lot more justifiable (and far better for everyone involved) if, for example, the SHA1 certs through Comodo’s pulled root were available to everyone.
I don't want to pick on Cloudflare or Comodo right now (see my other comment in here), but if someone were to propose a rule change that says a CA's trust obligations extend to all their old retired trusted roots as well as their current and future ones, I'd be inclined to agree unless I heard a very convincing argument against it (that had some strong protections in place to stop some of the obvious abuse possibiulities).
Thought experiment: what'd happen to a CA with root trust, if they negotiated to update a root cert, replaced their old one in all the trust stores, then sold their old private key to $badpeople?