The first amendment might overrule the cited law if that law didn't already include a requirement for intentional harm. But since the law does already have that requirement, there's not really an opportunity for a freedom of speech justification to be what protects a non-malicious publication of a proof of concept. The law isn't trying to infringe on freedom of speech.
But my argument isn't that freedom of speech could be used as an excuse for something that would otherwise be illegal -- my argument is that publishing and discussing exploit code is a constitutionally-protected activity. The CFAA statutes can be violated by gaining unauthorized access to a protected computer system, but that did not happen in the process of authoring and publishing the exploit code. The attacker was authorized to release new versions of the software, and they did. Their choice of what to make their software actually do is not regulated by the government, any more than a musician's choice of which lyrics to include in their song.
If an attacker then actually uses the backdoor created by someone else's decision to deploy the new release into their own environment, to gain unauthorized access to a protected computer system, then obviously there's a CFAA violation there. The public facts don't contain documented examples of this having happened (yet), though it will be unsurprising if that changes.
So it is still not obvious, at least to me, that any crime under US law has occurred so far. I am not a lawyer, though I'm aware of how badly the government has lost the previous court cases that attempted to restrict what humans can put in source code.
