You don't have any evidence to claiming Blockchain.com has malfunction on 2FA features and also about employees steal user funds in their wallet. All you talking on your article is only about your "presuming or guessing" as you want to blame their employee about your case. As you not bring any evidence in your article, so it's not surprised if Blockchain.com gave a legal threat to you.
I'm pretty sure I can express a theory of what happened? If this wasn't legal, then everyone who sued someone but was not able to prove it in court, would face defamation charges.
However, when you're create that article you're also gave a "threat" to people for not using their service.
What you mean by this?