> IANAL
Best to leave it at that.
It's not worth your time or the reader's time trying to come up with a technicality to make it perfectly legal to do something we know little about, other than it's extremely dangerous.
Law isn't code, you gotta violate some pretty bedrock principles to pull off something like this and get away with it.
Yes, if you were just a security researcher experimenting on GitHub, it's common sense you should get away with it*, and yes, it's hard to define a logical proof that ensnares this person, and not the researcher.
* and yes, we can come up with another hypothetical where the security researcher shouldn't get away with it. Hypotheticals all the way down.