It was "toxic to touch" in that it was hacked material of an American political party, which you might not want to be redistributing publicly (such as hosting on a server) if you can't afford lawyers.
In the US, once a secret is leaked, it becomes public knowledge. The DNC could try to assert copyrights over the emails, but that would be admitting they are genuine, and unlikely to actually work.
I think, that overall, it was an interesting and meaningful leak. Not just "toxic".