I agree that they have that right, and even the right to close degraded trails entirely in consultation with the Trails Bureau. And the WODC could have agreed to maintain them to "Wilderness" level. But as they discovered, with no plan for maintenance TB and others jumped in illegally no doubt thinking they were doing the world a favor. If WODC or Stopher's anonymous group had their number or e-mail posted on the signs to report trail issues, it would head off a lot of vigilante maintenance. They don't need to do this, but I suspect it would avoid a lot of grief.
Just like the registered letter that TB sent to some landowners asking if their trails were open to the public, and after they didn't answer he put them on the map. Obviously they were not required to answer, but for 43 cents and enough ink to write NO they could have saved themselves and others a lot of anguish.