This is in line with the arguments for/against Tor in general. I believe if you agree with Tor as a principle, then you should agree that making this exploit known is better overall.
As an aside, I believe everyone needs privacy, so I'd rather say that everyone benefits from it, not just the usual journalists, activists, whistleblowers, etc...
But then, this also can't be used against every other human being who needs privacy either. E.g.: Journalists, activists, anyone who disagrees with a large government, etc,