Who threatened him? Nobody has been accused of threatening - the people who were arrested in the case at issue are charged with rioting.
And even if one of the rioters had also made threats, how is getting 1.3 million ip addresses of visitors to the site that organized the protest possibly salient to that investigation? It's not a forum, there isn't going to be any further incriminating evidence on it. If the threatener visited the site, the went to the protest and made the threat, what exactly does the government gain by proving that he visited it?
