If the government wants access to the database, why bother doing anything other than getting it directly by issuing a subpoena for theymos to turn it over? Or a court order allowing them to image it surreptitiously (as they did with SR)? They don't need to fuck around and try to get it through people contracted to build a new forum.
There already multiple investigations in place into the actions of users who are alleged to have committed crimes involving Bitcoin. It wouldn't be hard to persuade a court to authorise the government to access the database either overtly or covertly to gather further evidence for those cases.