If you are using an e-mail provider that does something about it.
I have a GMail address that receives spam from several specific companies regularly. I've marked the messages as spam every month for at least five years. They keep coming, and GMail keeps showing them to me.
First, I wasn’t blaming the user at all, I was blaming the software. Second, I don’t see any “victim” here. It’s an occasional email sent in error. It’s a special kind of privilege to be able to write 500 words complaining (and threatening retribution) for something like this.
Email clients do need to be able to successfully handle spam, it’s a pre-requisite for using email. I would absolutely blame the email client software before shouting into the void.
Talk about GDPR, ICO, SEC... calling it a “breach”. Calling out the CTO for deleting old tweets, the comment “I assume that JGC doesn’t like his personal data being misused.” could be interpreted as a veiling threat but it’s borderline.
Talk about the GDPR isn't threatened retribution. It's just something that happens when you violate the GDPR. That's like saying that talk about tax law and the tax office and calling something “tax fraud” is a threat.
I do understand about the tweets, though. Calling out perceived hypocrisy, especially when there are legitimate reasons it's not hypocrisy, is a threaty sort of thing.